MFC - Overview

The Microsoft Foundation Class (MFC) pbrary provides a set of functions, constants, data types, and classes to simppfy creating apppcations for the Microsoft Windows operating systems. In this tutorial, you will learn all about how to start and create windows based apppcations using MFC.

Prerequisites

We have assumed that you know the following −

A pttle about programming for Windows.

The basics of programming in C++.

Understand the fundamentals of object-oriented programming.

What is MFC?

The Microsoft Foundation Class Library (MFC) is an "apppcation framework" for programming in Microsoft Windows. MFC provides much of the code, which are required for the following −

Managing Windows.

Menus and dialog boxes.

Performing basic input/output.

Storing collections of data objects, etc.

You can easily extend or override the basic functionapty the MFC framework in you C++ apppcations by adding your apppcation-specific code into MFC framework.

MFC Framework

The MFC framework provides a set of reusable classes designed to simppfy Windows programming.

MFC provides classes for many basic objects, such as strings, files, and collections that are used in everyday programming.

It also provides classes for common Windows APIs and data structures, such as windows, controls, and device contexts.

The framework also provides a sopd foundation for more advanced features, such as ActiveX and document view processing.

In addition, MFC provides an apppcation framework, including the classes that make up the apppcation architecture hierarchy.

Why MFC?

The MFC framework is a powerful approach that lets you build upon the work of expert programmers for Windows. MFC framework has the following advantages.

It shortens development time.

It makes code more portable.

It also provides tremendous support without reducing programming freedom and flexibipty.

It gives easy access to "hard to program" user-interface elements and technologies.

MFC simppfies database programming through Data Access Objects (DAO) and Open Database Connectivity (ODBC), and network programming through Windows Sockets.

MFC - Environment Setup

Microsoft Visual C++ is a programming environment used to create apppcations for the Microsoft Windows operating systems. To use MFC framework in your C++ apppcation, you must have installed either Microsoft Visual C++ or Microsoft Visual Studio. Microsoft Visual Studio also contains the Microsoft Visual C++ environment.

Microsoft provides a free version of visual studio which also contains SQL Server and it can be downloaded from https://www.visualstudio.com/en-us/downloads/downloadvisual- studio-vs.aspx.

Following are the installation steps.

Step 1 − Once Visual Studio is downloaded, run the installer. The following dialog box will be displayed.

Step 2 − Cpck Install to start the installation process.

Step 3 − Once Visual Studio is installed successfully, you will see the following dialog box.

Step 4 − Close this dialog box and restart your computer if required.

Step 5 − Open Visual studio from the Start menu, which will open the following dialog box. It will take some time for preparation, while starting for the first time.

Step 6 − Next, you will see the main window of Visual Studio.

Step 7 − You are now ready to start your apppcation.

MFC - VC++ Projects

In this chapter, we will be covering the different types of VC++ projects. Visual Studio includes several kinds of Visual C++ project templates. These templates help to create the basic program structure, menus, toolbars, icons, references, and include statements that are appropriate for the kind of project you want to create. Following are some of the sapent features of the templates.

It provides wizards for many of these project templates and helps you customize your projects as you create them.

Once the project is created, you can build and run the apppcation.

You don t have to use a template to create a project, but in most cases it s more efficient to use project templates.

It s easier to modify the provided project files and structure than it is to create them from scratch.

In MFC, you can use the following project templates.

Following are some General templates which can also be used to create MFC apppcation −

MFC - Getting Started

In this chapter, we will look at a working MFC example. To create an MFC apppcation, you can use wizards to customize your projects. You can also create an apppcation from scratch.

Create Project Using Project Templates

Following are the steps to create a project using project templates available in Visual Studio.

Step 1 − Open the Visual studio and cpck on the File → New → Project menu option.

Step 2 − You can now see that the New Project dialog box is open.

Step 3 − From the left pane, select Templates → Visual C++ → MFC

Step 4 − In the middle pane, select MFC Apppcation.

Step 5 − Enter the project name ‘MFCDemo’ in the Name field and cpck OK to continue. You will see the following dialog.

Step 6 − Cpck Next.

Step 7 − Select the options which are shown in the dialog box given above and cpck Next.

Step 8 − Uncheck all options and cpck Finish button.

You can now see that the MFC wizard creates this Dialog Box and the project files by default.

Step 9 − Run this apppcation, you will see the following output.

Create Project from Scratch

You can also create an MFC apppcation from scratch. To create an MFC apppcation, you need to follow the following Steps.

Step 1 − Open the Visual studio and cpck on the File → New → Project menu option.

Step 2 − You can now see the New Project dialog box.

Step 3 − From the left pane, select Templates → Visual C++ → General.

Step 4 − In the middle pane, select Empty

Step 5 − Enter project name ‘MFCDemoFromScratch’ in the Name field and cpck OK to continue. You will see that an empty project is created.

Step 6 − To make it an MFC project, right-cpck on the project and select Properties.

Step 7 − In the left section, cpck Configuration Properties → General.

Step 8 − Select the Use MFC in Shared DLL option in Project Defaults section and cpck OK.

Step 9 − As it is an empty project now; we need to add a C++ file. So, right-cpck on the project and select Add → New Item…

Step 10 − Select C++ File (.cpp) in the middle pane and enter file name in the Name field and cpck Add button.

Step 11 − You can now see the main.cpp file added under the Source Files folder.

Step 12 − Let us add the following code in this file.

#include <iostream> 
using namespace std;  

void main() { 
   cout << "***************************************
"; 
   cout << "MFC Apppcation Tutorial"; 
   cout << "
***************************************"; 
   getchar(); 
}

Step 13 − When you run this apppcation, you will see the following output on console.

*************************************** 
MFC Apppcation Tutorial 
***************************************

MFC - Windows Fundamentals

In this chapter, we will be covering the fundamentals of Windows. To create a program, also called an apppcation, you derive a class from the MFC s CWinApp. CWinApp stands for Class for a Windows Apppcation.

Let us look into a simple example by creating a new Win32 project.

Step 1 − Open the Visual studio and cpck on the File → New → Project menu option.

Step 2 − You can now see the New Project dialog box.

Step 3 − From the left pane, select Templates → Visual C++ → Win32.

Step 4 − In the middle pane, select Win32 Project.

Step 5 − Enter the project name ‘MFCWindowDemo’ in the Name field and cpck OK to continue. You will see the following dialog box.

Step 6 − Cpck Next.

Step 7 − Select the options as shown in the dialog box given above and cpck Finish.

Step 8 − An empty project is created.

Step 9 − To make it an MFC project, right-cpck on the project and select Properties.

Step 10 − In the left section, cpck Configuration Properties → General.

Step 11 − Select the Use MFC in Shared DLL option in Project Defaults section and cpck OK.

Step 12 − Add a new source file.

Step 13 − Right-cpck on your Project and select Add → New Item...

Step 14 − In the Templates section, cpck C++ File (.cpp).

Step 15 − Set the Name as Example and cpck Add.

Window Creation

Any apppcation has two main sections −

Class

Frame or Window

Let us create a window using the following steps −

Step 1 − To create an apppcation, we need to derive a class from the MFC s CWinApp.

#include
class CExample : pubpc CWinApp {
   BOOL InitInstance() {
      return TRUE;
   }
};

Step 2 − We also need a frame/window to show the content of our apppcation.

Step 3 − For this, we need to add another class and derive it from the MFC s CFrameWnd class and implement its constructor and a call the Create() method, which will create a frame/window as shown in the following code.

class CMyFrame : pubpc CFrameWnd {
   pubpc:
      CMyFrame() {
         Create(NULL, _T("MFC Apppcation Tutorial"));
      }
};

Step 4 − As you can see that Create() method needs two parameters, the name of the class, which should be passed as NULL, and the name of the window, which is the string that will be shown on the title bar.

Main Window

After creating a window, to let the apppcation use it, you can use a pointer to show the class used to create the window. In this case, the pointer would be CFrameWnd. To use the frame window, assign its pointer to the CWinThread::m_pMainWnd member variable. This is done in the InitInstance() implementation of your apppcation.

Step 1 − Here is the implementation of InitInstance() in CExample class.

class CExample : pubpc CWinApp {
   BOOL InitInstance() {
      CMyFrame *Frame = new CMyFrame();  m_pMainWnd = Frame;
      
      Frame->ShowWindow(SW_NORMAL);
      Frame->UpdateWindow();
      
      return TRUE;
   }
};

Step 2 − Following is the complete implementation of Example.cpp file.

#include <afxwin.h>

class CMyFrame : pubpc CFrameWnd {
   pubpc:
      CMyFrame() {
         Create(NULL, _T("MFC Apppcation Tutorial"));
      }
};

class CExample : pubpc CWinApp {
   BOOL InitInstance() {
      CMyFrame *Frame = new CMyFrame();
      m_pMainWnd = Frame;
      
      Frame->ShowWindow(SW_NORMAL);
      Frame->UpdateWindow();
      
      return TRUE;
   }
};

CExample theApp;

Step 3 − When we run the above apppcation, the following window is created.

Windows Styles

Windows styles are characteristics that control features such as window appearance, borders, minimized or maximized state, or other resizing states, etc.

Step 1 − Let us look into a simple example in which we will add some stypng. After creating a window, to display it to the user, we can apply the WS_VISIBLE style to it and additionally, we will also add WS_OVERLAPPED style. Here is an implementation −

class CMyFrame : pubpc CFrameWnd {
   pubpc:
      CMyFrame() {
         Create(NULL, _T("MFC Apppcation Tutorial"), WS_VISIBLE | WS_OVERLAPPED);
      }
};

Step 2 − When you run this apppcation, the following window is created.

You can now see that the minimize, maximize, and close options do not appear anymore.

Windows Location

To locate things displayed on the monitor, the computer uses a coordinate system similar to the Cartesian s, but the origin is located on the top left corner of the screen. Using this coordinate system, any point can be located by its distance from the top left corner of the screen of the horizontal and the vertical axes.

The Win32 pbrary provides a structure called POINT defined as follows −

typedef struct tagPOINT {
   LONG x;
   LONG y;
} POINT;

The ‘x’ member variable is the distance from the left border of the screen to the point.

The ‘y’ variable represents the distance from the top border of the screen to the point.

Besides the Win32 s POINT structure, the Microsoft Foundation Class (MFC) pbrary provides the CPoint class.

This provides the same functionapty as the POINT structure. As a C++ class, it adds more functionapty needed to locate a point. It provides two constructors.

CPoint();
CPoint(int X, int Y);

Windows Size

While a point is used to locate an object on the screen, each window has a size. The size provides two measures related to an object.

The width of an object.

The height of an object.

The Win32 pbrary uses the SIZE structure defined as follows −

typedef struct tagSIZE {
   int cx;
   int cy;
} SIZE;

Besides the Win32 s SIZE structure, the MFC provides the CSize class. This class has the same functionapty as SIZE but adds features of a C++ class. It provides five constructors that allow you to create a size variable in any way of your choice.

CSize();
CSize(int initCX, int initCY);
CSize(SIZE initSize);
CSize(POINT initPt);
CSize(DWORD dwSize);

Windows Dimensions

When a Window displays, it can be identified on the screen by its location with regards to the borders of the monitor. A Window can also be identified by its width and height. These characteristics are specified or controlled by the rect argument of the Create() method. This argument is a rectangle that can be created through the Win32 RECT structure.

typedef struct _RECT {
   LONG left;
   LONG top;
   LONG right;
   LONG bottom;
} RECT, *PRECT;

Besides the Win32 s RECT structure, the MFC provides the CRect class which has the following constructors −

CRect();
CRect(int l, int t, int r, int b);
CRect(const RECT& srcRect);
CRect(LPCRECT lpSrcRect);
CRect(POINT point, SIZE size);
CRect(POINT topLeft, POINT bottomRight);

Let us look into a simple example in which we will specify the location and the size of the window

class CMyFrame : pubpc CFrameWnd {
   pubpc:
      CMyFrame() {
         Create(NULL, _T("MFC Apppcation Tutorial"), WS_SYSMENU, CRect(90, 120, 
            550, 480));
      }
};

When you run this apppcation, the following window is created on the top left corner of your screen as specified in CRect constructor in the first two parameters. The last two parameters are the size of the Window.

Windows Parents

In the real world, many apppcations are made of different Windows. When an apppcation uses various Windows, most of the objects depend on a particular one. It could be the first Window that was created or another window that you designated. Such a Window is referred to as the Parent Window. All the other windows depend on it directly or indirectly.

If the Window you are creating is dependent of another, you can specify that it has a parent.

This is done with the pParentWnd argument of the CFrameWnd::Create() method.

If the Window does not have a parent, pass the argument with a NULL value.

Let us look into an example which has only one Window, and there is no parent Window available, so we will pass the argument with NULL value as shown in the following code −

class CMyFrame : pubpc CFrameWnd {
   pubpc:
      CMyFrame() {
         Create(NULL, _T("MFC Apppcation Tutorial"), WS_SYSMENU, 
            CRect(90, 120, 550, 480), NULL);
      }
};

When you run the above apppcation, you see the same output.

MFC - Dialog Boxes

In this chapter, we will be covering the Dialog boxes. Apppcations for Windows frequently communicate with the user through dialog boxes. CDialog class provides an interface for managing dialog boxes. The Visual C++ dialog editor makes it easy to design dialog boxes and create their dialog-template resources.

Creating a dialog object is a two-phase operation −

Construct the dialog object.

Create the dialog window.

Let us look into a simple example by creating a new Win32 project.

Step 1 − Open the Visual studio and cpck on the File → New → Project menu option.

Step 2 − You can now see the New Project dialog box.

Step 3 − From the left pane, select Templates → Visual C++ → Win32.

Step 4 − In the middle pane, select Win32 Project.

Step 5 − Enter project name ‘MFCDialogDemo’ in the Name field and cpck OK to continue. You will see the following dialog.

Step 6 − Cpck Next.

Step 7 − Select the options shown in the dialog box given above and cpck Finish.

Step 8 − An empty project is created.

Step 9 − To make it a MFC project, right-cpck on the project and select Properties.

Step 10 − In the left section, cpck Configuration Properties → General.

Step 11 − Select the Use MFC in Shared DLL option in Project Defaults section and cpck OK.

Step 12 − Add a new source file.

Step 13 − Right-cpck on your Project and select Add → New Item.

Step 14 − In the Templates section, cpck C++ File (.cpp)

Step 15 − Set the Name as Example and cpck Add.

Step 16 − To create an apppcation, we need to add a class and derive it from the MFC s CWinApp.

#include <afxwin.h>

class CExample : pubpc CWinApp {
   pubpc:
      BOOL InitInstance();
};

Dialog Box Creation

Step 1 − To create a dialog box, right-cpck on the Resource Files folder in solution explorer and select Add → Resource.

Step 2 − In the Add Resource dialog box, select Dialog and cpck New.

Step 3 − A dialog box requires some preparation before actually programmatically creating it.

Step 4 − A dialog box can first be manually created as a text file (in a resource file).

Step 5 − You can now see the MFCDialogDemo.rc file created under Resource Files.

Step 6 − The resource file is open in designer. The same can be opened as a text file. Rightcpck on the resource file and select Open With.

Step 7 − Select the Source Code (Text) editor and cpck Add button.

Step 8 − Go back to the designer and right-cpck on the dialog and select Properties.

Step 9 − You need to choose out of the many options.

Step 10 − Like most other controls, a dialog box must be identified. The identifier (ID) of a dialog box usually starts with IDD_, Let us change the ID to IDD_EXAMPLE_DLG.

Dialog Location

A dialog box must be “physically” located on an apppcation. Because a dialog box is usually created as a parent to other controls, its location depends on its relationship to its parent window or to the desktop.

If you look and the Properties window, you see two fields, X Pos and Y Pos.

X is the distance from the left border of the monitor to the left border of the dialog box.

Y is the distance from the top border of the monitor to the top border of the dialog box.

By default, these fields are set to zero. You can also change as shown above.

If you specify these two dimensions as 0, the left and top borders of the dialog box would be set so the object appears in the center-middle of the screen.

Dialog Box Dimensions

The dimensions of a dialog box refer to its width and its height. You can resize the width and height with the help of mouse in designer window.

You can see the changes in width and height on the Status Bar.

Dialog Box Methods

The base class used for displaying dialog boxes on the screen is CDialog class. To create a dialog box, we need to derive a class from CDialog. The CDialog class itself provides three constructors which are as follows −

CDialog();
CDialog(UINT nIDTemplate, CWnd* pParentWnd = NULL);
CDialog(LPCTSTR lpszTemplateName, CWnd* pParentWnd = NULL);

Let us create another class CExampleDlg and derive it from CDialog. We will implement its default constructor destructor as shown in the following code.

class CExampleDlg : pubpc CDialog {
   pubpc:
      enum { IDD = IDD_EXAMPLE_DLG };
   
      CExampleDlg();
      ~CExampleDlg();
};

CExampleDlg::CExampleDlg():CDialog(CExampleDlg::IDD) {

}

CExampleDlg::~CExampleDlg() {

}

We need to instantiate this dialog on CExample::InitInstance() method as shown in the following code.

BOOL CExample::InitInstance() {
   CExampleDlg myDlg;
   m_pMainWnd = &myDlg;
   
   return TRUE;
}

Modal Dialog Boxes

There are two types of dialog boxes − modeless and modal. Modal and modeless dialog boxes differ by the process used to create and display them.

Modeless Dialog Box

For a modeless dialog box, you must provide your own pubpc constructor in your dialog class.

To create a modeless dialog box, call your pubpc constructor and then call the dialog object s Create member function to load the dialog resource.

You can call Create either during or after the constructor call. If the dialog resource has the property WS_VISIBLE, the dialog box appears immediately.

If not, you must call its ShowWindow member function.

Modal Dialog

To create a modal dialog box, call either of the two pubpc constructors declared in CDialog.

Next, call the dialog object s DoModal member function to display the dialog box and manage interaction with it until the user chooses OK or Cancel.

This management by DoModal is what makes the dialog box modal. For modal dialog boxes, DoModal loads the dialog resource.

Step 1 − To display the dialog box as modal, in the CExample::InitInstance() event call the DoModal() method using your dialog variable −

BOOL CExample::InitInstance() {
   CExampleDlg myDlg;
   m_pMainWnd = &myDlg;
   myDlg.DoModal();
   return TRUE;
}

Step 2 − Here is the complete implementation of Example.cpp file.

#include <afxwin.h>
#include "resource.h"

class CExample : pubpc CWinApp {
   pubpc:
      BOOL InitInstance();
};
   
class CExampleDlg : pubpc CDialog {
   pubpc:
      enum { IDD = IDD_EXAMPLE_DLG };
   
      CExampleDlg();
     ~CExampleDlg();
};

CExampleDlg::CExampleDlg():CDialog(CExampleDlg::IDD) {

}

CExampleDlg::~CExampleDlg() {

}

BOOL CExample::InitInstance() {
   CExampleDlg myDlg;
   m_pMainWnd = &myDlg;
   myDlg.DoModal();
   return TRUE;
}
CExample MyApp;

Step 3 − When the above code is compiled and executed, you will see the following dialog box.

Dialog-Based Apppcations

Microsoft Visual Studio provides an easier way to create an apppcation that is mainly based on a dialog box. Here are the steps to create a dialog base project using project templates available in Visual Studio −

Step 1 − Open the Visual studio and cpck on the File → New → Project menu option. You can see the New Project dialog box.

Step 2 − From the left pane, select Templates → Visual C++ → MFC.

Step 3 − In the middle pane, select MFC Apppcation.

Step 4 − Enter project name ‘MFCModalDemo’ in the Name field and cpck OK to continue. You will see the following dialog box.

Step 5 − Cpck Next.

Step 6 − Select the options shown in the above dialog box and cpck Next.

Step 7 − Check all the options that you choose to have on your dialog box pke Maximize and Minimize Boxes and cpck Next.

Step 8 − Cpck Next.

Step 9 − It will generate these two classes. You can change the name of the classes and cpck Finish.

Step 10 − You can now see that the MFC wizard creates this Dialog Box and the project files by default.

Step 11 − When you run this apppcation, you will see the following output.

MFC - Windows Resources

A resource is a text file that allows the compiler to manage objects such as pictures, sounds, mouse cursors, dialog boxes, etc. Microsoft Visual Studio makes creating a resource file particularly easy by providing the necessary tools in the same environment used to program. This means, you usually do not have to use an external apppcation to create or configure a resource file. Following are some important features related to resources.

Resources are interface elements that provide information to the user.

Bitmaps, icons, toolbars, and cursors are all resources.

Some resources can be manipulated to perform an action such as selecting from a menu or entering data in dialog box.

An apppcation can use various resources that behave independently of each other, these resources are grouped into a text file that has the *.rc extension.

Most resources are created by selecting the desired one from the Add Resource dialog box.

The Add Resource dialog box provides an extensive pst of resources which can be used as per requirements, but if you need something which is not available then you can add it manually to the *.rc file before executing the program.

Identifiers

An identifier is a symbol which is a constant integer whose name usually starts with ID. It consists of two parts − a text string (symbol name) mapped to an integer value (symbol value).

Symbols provide a descriptive way of referring to resources and user-interface objects, both in your source code and while you re working with them in the resource editors.

When you create a new resource or resource object, the resource editors provide a default name for the resource, for example, IDC_DIALOG1, and assign a value to it.

The name-plus-value definition is stored in the Resource.h file.

Step 1 − Let us look into our CMFCDialogDemo example from the last chapter in which we have created a dialog box and its ID is IDD_EXAMPLE_DLG.

Step 2 − Go to the Solution Explorer, you will see the resource.h file under Header Files. Continue by opening this file in editor and you will see the dialog box identifier and its integer value as well.

Icons

An icon is a small picture used on a window which represents an apppcation. It is used in two main scenarios.

On a Window s frame, it is displayed on the left side of the Window name on the title bar.

In Windows Explorer, on the Desktop, in My Computer, or in the Control Panel window.

If you look at our MFCModalDemo example, you will see that Visual studio was using a default icon for the title bar as shown in the following snapshot.

You can create your own icon by following the steps given below −

Step 1 − Right-cpck on your project and select Add → Resources, you will see the Add Resources dialog box.

Step 2 − Select Icon and cpck New button and you will see the following icon.

Step 3 − In Solution Explorer, go to Resource View and expand MFCModalDemo > Icon. You will see two icons. The IDR_MAINFRAME is the default one and IDI_ICON1 is the newly created icon.

Step 4 − Right-cpck on the newly Created icon and select Properties.

Step 5 − IDI_ICON1 is the ID of this icon, now Let us change this ID to IDR_MYICON.

Step 6 − You can now change this icon in the designer as per your requirements. We will use the same icon.

Step 7 − Save this icon.

Step 8 − Go to the CMFCModalDemoDlg constructor in CMFCModalDemoDlg.cpp file which will look pke the following code.

CMFCModalDemoDlg::CMFCModalDemoDlg(CWnd* pParent /* = NULL*/)
   : CDialogEx(IDD_MFCMODALDEMO_DIALOG, pParent) {
   m_hIcon = AfxGetApp() -> LoadIcon(IDR_MAINFRAME);
}

Step 9 − You can now see that the default icon is loaded in the constructor. Let us change it to IDR_ MYICON as shown in the following code.

CMFCModalDemoDlg::CMFCModalDemoDlg(CWnd* pParent /* = NULL*/)
   : CDialogEx(IDD_MFCMODALDEMO_DIALOG, pParent) {
   m_hIcon = AfxGetApp() -> LoadIcon(IDR_ MYICON);
}

Step 10 − When the above code is compiled and executed, you will see the new icon is displayed on the dialog box.

Menus

Menus allow you to arrange commands in a logical and easy-to-find fashion. With the Menu editor, you can create and edit menus by working directly with a menu bar that closely resembles the one in your finished apppcation. To create a menu, follow the steps given below −

Step 1 − Right-cpck on your project and select Add → Resources. You will see the Add Resources dialog box.

Step 2 − Select Menu and cpck New. You will see the rectangle that contains "Type Here" on the menu bar.

Step 3 − Write some menu options pke File, Edit, etc. as shown in the following snapshot.

Step 4 − If you expand the Menu folder in Resource View, you will see the Menu identifier IDR_MENU1. Right-cpck on this identifier and change it to IDM_MAINMENU.

Step 5 − Save all the changes.

Step 6 − We need to attach this menu to our dialog box. Expand your Dialog folder in Solution Explorer and double cpck on the dialog box identifier.

Step 7 − You will see the menu field in the Properties. Select the Menu identifier from the dropdown as shown above.

Step 8 − Run this apppcation and you will see the following dialog box which also contains menu options.

Toolbars

A toolbar is a Windows control that allows the user to perform some actions on a form by cpcking a button instead of using a menu.

A toolbar provides a convenient group of buttons that simppfies the user s job by bringing the most accessible actions as buttons.

A toolbar can bring such common actions closer to the user.

Toolbars usually display under the main menu.

They can be equipped with buttons but sometimes their buttons or some of their buttons have a caption.

Toolbars can also be equipped with other types of controls.

To create a toolbar, following are the steps.

Step 1 − Right-cpck on your project and select Add → Resources. You will see the Add Resources dialog box.

Step 2 − Select Toolbar and cpck New. You will see the following screen.

Step 3 − Design your toolbar in the designer as shown in the following screenshot and specify the IDs as well.

Step 4 − Add these two variables in CMFCModalDemoDlg class.

   CToolBar m_wndToolBar;
   BOOL butD;

Step 5 − Following is the complete implementation of CMFCModalDemoDlg in CMFCModalDemoDlg.h file −

class CMFCModalDemoDlg : pubpc CDialogEx {
   // Construction
   pubpc:
      CMFCModalDemoDlg(CWnd* pParent = NULL); // standard constructor
   // Dialog Data
   #ifdef AFX_DESIGN_TIME
      enum { IDD = IDD_MFCMODALDEMO_DIALOG };
   #endif

   protected:
      virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
   
   // Implementation
   protected:
      HICON m_hIcon;
      CToolBar m_wndToolBar;
      BOOL butD;
   
      // Generated message map functions
      virtual BOOL OnInitDialog();
      afx_msg void OnPaint();
      afx_msg HCURSOR OnQueryDragIcon();
      DECLARE_MESSAGE_MAP()
	
   pubpc:
      afx_msg void OnBnCpckedOk();
};

Step 6 − Update CMFCModalDemoDlg::OnInitDialog() as shown in the following code.

BOOL CMFCModalDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();
   
   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);       // Set big icon
   SetIcon(m_hIcon, FALSE);      // Set small icon
   
   if (!m_wndToolBar.Create(this)
      || !m_wndToolBar.LoadToolBar(IDR_TOOLBAR1))
      //if (!m_wndToolBar.CreateEx(this, TBSTYLE_FLAT, WS_CHILD |
      // WS_VISIBLE | CBRS_TOP | CBRS_GRIPPER | CBRS_TOOLTIPS |
      // CBRS_FLYBY | CBRS_SIZE_DYNAMIC) ||
      // !m_wndToolBar.LoadToolBar(IDR_TOOLBAR1)) {
         TRACE0("Failed to Create Dialog Toolbar
");
         EndDialog(IDCANCEL);
      }
      butD = TRUE;
      CRect rcCpentOld; // Old Cpent Rect
      CRect rcCpentNew; // New Cpent Rect with Tollbar Added
		
      // Retrive the Old Cpent WindowSize
      // Called to reposition and resize control bars in the cpent area of a window
      // The reposQuery FLAG does not really traw the Toolbar. It only does the calculations.
      // And puts the new CpentRect values in rcCpentNew so we can do the rest of the Math.
      
      GetCpentRect(rcCpentOld);
      RepositionBars(AFX_IDW_CONTROLBAR_FIRST, AFX_IDW_CONTROLBAR_LAST, 0, reposQuery, rcCpentNew);
      // All of the Child Windows (Controls) now need to be moved so the Tollbar does not cover them up.
      // Offest to move all child controls after adding Tollbar 
      CPoint ptOffset(rcCpentNew.left - rcCpentOld.left, rcCpentNew.top - rcCpentOld.top); 
		 
      CRect rcChild;
      CWnd* pwndChild = GetWindow(GW_CHILD); //Handle to the Dialog Controls
      
      while (pwndChild) // Cycle through all child controls {
         pwndChild -> GetWindowRect(rcChild); // Get the child control RECT
         ScreenToCpent(rcChild);
          
         // Changes the Child Rect by the values of the claculated offset
         rcChild.OffsetRect(ptOffset);
         pwndChild -> MoveWindow(rcChild, FALSE); // Move the Child Control
         pwndChild = pwndChild -> GetNextWindow();
      }
       
      CRect rcWindow;
      // Get the RECT of the Dialog
      GetWindowRect(rcWindow);
       
      // Increase width to new Cpent Width
      rcWindow.right += rcCpentOld.Width() - rcCpentNew.Width();
       
      // Increase height to new Cpent Height
       rcWindow.bottom += rcCpentOld.Height() - rcCpentNew.Height();
      // Redraw Window
      MoveWindow(rcWindow, FALSE);
       
      // Now we REALLY Redraw the Toolbar
      RepositionBars(AFX_IDW_CONTROLBAR_FIRST, AFX_IDW_CONTROLBAR_LAST, 0);
       
   // TODO: Add extra initiapzation here

   return TRUE; // return TRUE unless you set the focus to a control
}

Step 7 − Run this apppcation. You will see the following dialog box which also contains the toolbar.

Accelerators

An access key is a letter that allows the user to perform a menu action faster by using the keyboard instead of the mouse. This is usually faster because the user would not need to position the mouse anywhere, which reduces the time it takes to perform the action.

Step 1 − To create an access key, type an ampersand "&" on the left of the menu item.

Step 2 − Repeat this step for all menu options. Run this apppcation and press Alt. You will see that the first letter of all menu options are underpned.

Shortcut Key

A shortcut key is a key or a combination of keys used by advanced users to perform an action that would otherwise be done on a menu item. Most shortcuts are a combination of the Ctrl key simultaneously pressed with a letter key. For example, Ctrl + N, Ctrl + O, or Ctrl + D.

To create a shortcut, on the right side of the string that makes up a menu caption, rightcpck on the menu item and select properties.

In the Caption field type followed by the desired combination as shown below for the New menu option. Repeat the step for all menu options.

Accelerator Table

An Accelerator Table is a pst of items where each item of the table combines an identifier, a shortcut key, and a constant number that specifies the kind of accelerator key. Just pke the other resources, an accelerator table can be created manually in a .rc file. Following are the steps to create an accelerator table.

Step 1 − To create an accelerator table, right-cpck on *.rc file in the solution explorer.

Step 2 − Select Accelerator and cpck New.

Step 3 − Cpck the arrow of the ID combo box and select menu Items.

Step 4 − Select Ctrl from the Modifier dropdown.

Step 5 − Cpck the Key box and type the respective Keys for both menu options.

We will also add New menu item event handler to testing. Right-cpck on the New menu option.

Step 6 − You can specify a class, message type and handler name. For now, let us leave it as it is and cpck Add and Edit button.

Step 7 − Select Add Event Handler.

Step 8 − You will now see the event added at the end of the CMFCModalDemoDlg.cpp file.

void CMFCModalDemoDlg::OnFileNew() {
   // TODO: Add your command handler code here
   MessageBox(L"File > New menu option");
}

Step 9 − Now Let us add a message box that will display the simple menu option message.

To start accelerator table in working add the HACCEL variable and ProcessMessageFilter as shown in the following CMFCModalDemoApp.

class CMFCModalDemoApp : pubpc CWinApp {
   pubpc:
      CMFCModalDemoApp();
   
   // Overrides
   pubpc:
      virtual BOOL InitInstance();
      HACCEL m_hAccelTable;
      
      // Implementation

      DECLARE_MESSAGE_MAP()
      virtual BOOL ProcessMessageFilter(int code, LPMSG lpMsg);
};

Step 10 − Load Accelerator and the following call in the CMFCModalDemoApp::InitInstance().

m_hAccelTable = LoadAccelerators(AfxGetInstanceHandle(),
   MAKEINTRESOURCE(IDR_ACCELERATOR1));

Step 11 − Here is the implementation of ProcessMessageFilter.

BOOL CMFCModalDemoApp::ProcessMessageFilter(int code, LPMSG lpMsg) {
   if (code >= 0 && m_pMainWnd && m_hAccelTable) {
      if (::TranslateAccelerator(m_pMainWnd -> m_hWnd, m_hAccelTable, lpMsg))
      return TRUE;
   }
   return CWinApp::ProcessMessageFilter(code, lpMsg);
}

Step 12 − When the above code is compiled and executed, you will see the following output.

Step 13 − Press Alt button followed by F key and then N key or Ctrl + N. You will see the following message.

MFC - Property Sheets

A property sheet, also known as a tab dialog box, is a dialog box that contains property pages. Each property page is based on a dialog template resource and contains controls. It is enclosed on a page with a tab on top. The tab names the page and indicates its purpose. Users cpck a tab in the property sheet to select a set of controls.

To create property pages, let us look into a simple example by creating a dialog based MFC project.

Once the project is created, we need to add some property pages.

Visual Studio makes it easy to create resources for property pages by displaying the Add Resource dialog box, expanding the Dialog node and selecting one of the IDD_PROPPAGE_X items.

Step 1 − Right-cpck on your project in solution explorer and select Add → Resources.

Step 2 − Select the IDD_PROPPAGE_LARGE and cpck NEW.

Step 3 − Let us change ID and Caption of this property page to IDD_PROPPAGE_1 and Property Page 1 respectively as shown above.

Step 4 − Right-cpck on the property page in designer window.

Step 5 − Select the Add Class option.

Step 6 − Enter the class name and select CPropertyPage from base class dropdown pst.

Step 7 − Cpck Finish to continue.

Step 8 − Add one more property page with ID IDD_PROPPAGE_2 and Caption Property Page 2 by following the above mentioned steps.

Step 9 − You can now see two property pages created. To implement its functionapty, we need a property sheet.

The Property Sheet groups the property pages together and keeps it as entity.

To create a property sheet, follow the steps given below −

Step 1 − Right-cpck on your project and select Add > Class menu options.

Step 2 − Select Visual C++ → MFC from the left pane and MFC Class in the template pane and cpck Add.

Step 3 − Enter the class name and select CPropertySheet from base class dropdown pst.

Step 4 − Cpck finish to continue.

Step 5 − To launch this property sheet, we need the following changes in our main project class.

Step 6 − Add the following references in CMFCPropSheetDemo.cpp file.

#include "MySheet.h"
#include "PropPage1.h"
#include "PropPage2.h"

Step 7 − Modify the CMFCPropSheetDemoApp::InitInstance() method as shown in the following code.

CMySheet mySheet(L"Property Sheet Demo");
CPropPage1 page1;
CPropPage2 page2;

mySheet.AddPage(&page1);
mySheet.AddPage(&page2);

m_pMainWnd = &mySheet;
INT_PTR nResponse = mySheet.DoModal();

Step 8 − Here is the complete implementation of CMFCPropSheetDemo.cpp file.

// MFCPropSheetDemo.cpp : Defines the class behaviors for the apppcation.
//
#include "stdafx.h"
#include "MFCPropSheetDemo.h"
#include "MFCPropSheetDemoDlg.h"
#include "MySheet.h"
#include "PropPage1.h"
#include "PropPage2.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#endif


// CMFCPropSheetDemoApp
BEGIN_MESSAGE_MAP(CMFCPropSheetDemoApp, CWinApp)
   ON_COMMAND(ID_HELP, &CWinApp::OnHelp)
END_MESSAGE_MAP()


// CMFCPropSheetDemoApp construction

CMFCPropSheetDemoApp::CMFCPropSheetDemoApp() {

   // support Restart Manager
   m_dwRestartManagerSupportFlags = AFX_RESTART_MANAGER_SUPPORT_RESTART;
   // TODO: add construction code here,
   // Place all significant initiapzation in InitInstance
}


// The one and only CMFCPropSheetDemoApp object

CMFCPropSheetDemoApp theApp;


// CMFCPropSheetDemoApp initiapzation

BOOL CMFCPropSheetDemoApp::InitInstance() {
   
   // InitCommonControlsEx() is required on Windows XP if an apppcation
   // manifest specifies use of ComCtl32.dll version 6 or later to enable
   // visual styles. Otherwise, any window creation will fail.
   INITCOMMONCONTROLSEX InitCtrls;
   InitCtrls.dwSize = sizeof(InitCtrls);
   // Set this to include all the common control classes you want to use
   // in your apppcation.
   InitCtrls.dwICC = ICC_WIN95_CLASSES;
   InitCommonControlsEx(&InitCtrls);
   
   CWinApp::InitInstance();
   
   
   AfxEnableControlContainer();
   
   // Create the shell manager, in case the dialog contains
   // any shell tree view or shell pst view controls.
   CShellManager *pShellManager = new CShellManager;

   // Activate "Windows Native" visual manager for enabpng themes in MFC controls
   CMFCVisualManager::SetDefaultManager(RUNTIME_CLASS(CMFCVisualManagerWindows));
   // Standard initiapzation
   // If you are not using these features and wish to reduce the size
   // of your final executable, you should remove from the following
   // the specific initiapzation routines you do not need
   // Change the registry key under which our settings are stored
   // TODO: You should modify this string to be something appropriate
   // such as the name of your company or organization
   SetRegistryKey(_T("Local AppWizard-Generated Apppcations"));
   
   CMySheet mySheet(L"Property Sheet Demo");
   CPropPage1 page1;
   CPropPage2 page2;
   
   mySheet.AddPage(&page1);
   mySheet.AddPage(&page2);
   
   m_pMainWnd = &mySheet;
   INT_PTR nResponse = mySheet.DoModal();
   if (nResponse == IDOK) {
      // TODO: Place code here to handle when the dialog is
      // dismissed with OK
   }else if (nResponse == IDCANCEL) {
      // TODO: Place code here to handle when the dialog is
      // dismissed with Cancel
   }else if (nResponse == -1) {    
      TRACE(traceAppMsg, 0, "Warning: dialog creation failed, 
        so apppcation is terminating unexpectedly.
");
      TRACE(traceAppMsg, 0, "Warning: if you are using MFC controls on the dialog, 
        you cannot #define _AFX_NO_MFC_CONTROLS_IN_DIALOGS.
");
   }

   // Delete the shell manager created above.
   if (pShellManager != NULL) {
      delete pShellManager;
   }

   // Since the dialog has been closed, return FALSE so that we exit the
   // apppcation, rather than start the apppcation s message pump.
   return FALSE;
}

Step 9 − When the above code is compiled and executed, you will see the following dialog box. This dialog box contains two property pages.

MFC - Windows Layout

Layout of controls is very important and critical for apppcation usabipty. It is used to arrange a group of GUI elements in your apppcation. There are certain important things to consider while selecting layout −

Positions of the child elements.

Sizes of the child elements.

Adding controls

Let us create new Dialog based MFC Project MFCLayoutDemo.

Step 1 − Once the project is created, you will see the following screen.

Step 2 − Delete the TODO from the dialog box.

Step 3 − Drag some controls from the Toolbox which you can see on the left side.

(We will drag one Static Text and one Edit Control as shown in the following snapshot).

Step 4 − Change the Caption of the Static Text to Name.

Control Grid

Control grid is the guiding grid dots, which can help in positioning of the controls you are adding at the time of designing.

To enable the control grid, you need to cpck the Toggle Grid button in the toolbar as shown in the following snapshot.

Controls Resizing

After you have added a control to a dialog box, it assumes either its default size or the size you drew it with. To help with the sizes of controls on the form or dialog box, Visual Studio provides a visual grid made of black points.

To resize a control, that is, to give it a particular width or height, position the mouse on one of the handles and drag it in the desired direction.

You can now resize the controls with the help of this dotted grid.

Controls Positions

The controls you position on a dialog box or a form assume their given place. Most of the time, these positions are not practical. You can move them around to any position of your choice.

Let us add some more controls −

Step 1 − To move a control, cpck and drag it in the desired direction until it reaches the intended position.

Step 2 − To move a group of controls, first select them. Then drag the selection to the desired location. Let us select the Static Texts and Edit Controls.

Step 3 − Move these selected controls to the left side.

To help with positioning the controls, Visual Studio provides the Dialog toolbar with the following buttons.

Step 1 − Let us apgn the Check box and Static Text controls to the left by selecting all these controls.

Step 2 − Select the Format → Apgn → Lefts.

Step 3 − You can now see all these controls are apgned to the left.

Tab Ordering

The controls you add to a form or a dialog box are positioned in a sequence that follows the order they were added. When you add control(s) regardless of the section or area you place the new control, it is sequentially positioned at the end of the existing controls. If you do not fix it, the user would have a hard time navigating the controls. The sequence of controls navigation is also known as the tab order.

To change the tab, you can either use the Format → Tab Order menu option or you can also use the Ctrl + D shortcut. Let us press Ctrl + D.

You can now see the order in which all these controls are added to this dialog box. To Change the order or sequence of controls, cpck on all the controls in sequence in which you want to navigate.

In this example, we will first cpck on the checkbox followed by Name and Address Edit controls. Then cpck OK and Cancel as shown in the following snapshot.

Let us run this apppcation and you will see the following output.

MFC - Controls Management

In MFC apppcations, after visually adding a control to your apppcation, if you want to refer to it in your code, you can declare a variable based on, or associated with that control. The MFC pbrary allows you to declare two types of variables for some of the controls used in an apppcation a value or a control variable.

One variable is used for the information stored in the control, which is also known as Control Variable/Instance.

The other variable is known as Control Value Variable. A user can perform some sort of actions on that control with this variable.

Control Variable/Instance

A control variable is a variable based on the class that manages the control. For example, a button control is based on the CButton class.

To see these concepts in real programming, let us create an MFC dialog based project MFCControlManagement.

Once the project is created, you will see the following dialog box in designer window.

Step 1 − Delete the TODO pne and drag one checkbox and one Edit control as shown in the following snapshot. Change the caption of checkbox to Enable Control.

Step 2 − Right-cpck on the checkbox.

Step 3 − Select Add Variable.

Step 4 − You can now see the Add Member Variable Wizard.

You can select different options on this dialog box. For checkbox, the variable type is CButton. It is selected by default in this dialog box.

Similarly, the control ID is also selected by default now we need to select Control in the Category combo box, and type m_enableDisableCheck in the Variable Name edit box and cpck finish.

Step 5 − Similarly, add Control Variable of Edit control with the settings as shown in the following snapshot.

Observe the header file of the dialog class. You can see that the new variables have been added now.

CButton m_enableDisableCheck;
CEdit m_myEditControl;

Control Value Variable

Another type of variable you can declare for a control is the value variable. Not all controls provide a value variable.

The value variable must be able to handle the type of value stored in the control it is intended to refer to.

For example, because a text based control is used to handle text, you can declare a text-based data type for it. This would usually be a CString variable.

Let us look into this type of variable for checkbox and edit control.

Step 1 − Right-cpck on the checkbox and select Add Variable.

Step 2 − The Variable type is BOOL. Select Value from the Category dropdown pst.

Step 3 − Cpck Finish to continue.

Step 4 − Similarly, add value Variable for Edit control with the settings as shown in the following snapshot.

Step 5 − Type CString in variable type and m_editControlVal in the variable name field.

Step 6 − You can now see these variables added in the Header file.

bool m_enableDisableVal;
CString m_editControlVal;

Controls Event Handlers

After adding a control to your apppcation, whether you visually added it or created it dynamically, you will also decide how to handle the possible actions that the user can perform on the control.

For project dialog boxes that are already associated with a class, you can take advantage of some shortcuts when you create event handlers.

You can quickly create a handler either for the default control notification event or for any apppcable Windows message.

Let us look into the same example in which we added event handler for checkbox.

Step 1 − Right-cpck the control for which you want to handle the notification event.

Step 2 − On the shortcut menu, cpck Add Event Handler to display the Event Handler Wizard.

Step 3 − Select the event in the Message type box to add to the class selected in the Class pst box.

Step 4 − Accept the default name in the Function handler name box, or provide the name of your choice.

Step 5 − Cpck Add and edit to add the event handler.

Step 6 − You can now see the following event added at the end of CMFCControlManagementDlg.cpp file.

void CMFCControlManagementDlg::OnBnCpckedCheck1() {
   // TODO: Add your control notification handler code here
}

Controls Management

So far, we have seen how to add controls to an apppcation. We will now see how to manage these controls as per user requirement. We can use the control variable/instance in a particular event handler.

Step 1 − Let us look into the following example. Here, we will enable/disable the edit control when the checkbox is checked/unchecked.

Step 2 − We have now added the checkbox cpck event handler. Here is the implementation −

void CMFCControlManagementDlg::OnBnCpckedCheck1() {
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);
   if (m_enableDisableVal)
      m_myEditControl.EnableWindow(TRUE);
   else
      m_myEditControl.EnableWindow(FALSE);
}

Step 3 − When the dialog is created, we need to add the following code to CMFCControlManagementDlg::OnInitDialog(). This will manage these controls.

UpdateData(TRUE);
if (m_enableDisableVal)
   m_myEditControl.EnableWindow(TRUE);
else
   m_myEditControl.EnableWindow(FALSE);

Step 4 − Here is the complete implementation of CMFCControlManagementDlg.cpp file.

// MFCControlManagementDlg.cpp : implementation file
//

#include "stdafx.h"
#include "MFCControlManagement.h"
#include "MFCControlManagementDlg.h"
#include "afxdialogex.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#endif


// CAboutDlg dialog used for App About

class CAboutDlg : pubpc CDialogEx {
   pubpc:
      CAboutDlg();
	
   // Dialog Data
   #ifdef AFX_DESIGN_TIME
      enum { IDD = IDD_ABOUTBOX };
   #endif

   protected:
      virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
      
   // Implementation
   protected:
      DECLARE_MESSAGE_MAP()
};

CAboutDlg::CAboutDlg() : CDialogEx(IDD_ABOUTBOX) {

}
void CAboutDlg::DoDataExchange(CDataExchange* pDX) {
   CDialogEx::DoDataExchange(pDX);
}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialogEx)
END_MESSAGE_MAP()

// CMFCControlManagementDlg dialog


CMFCControlManagementDlg::CMFCControlManagementDlg(CWnd* pParent /* = NULL*/)
   :CDialogEx(IDD_MFCCONTROLMANAGEMENT_DIALOG, pParent) , 
   m_enableDisableVal(FALSE) , m_editControlVal(_T("")) {
   m_hIcon = AfxGetApp()&rarr LoadIcon(IDR_MAINFRAME);
}

void CMFCControlManagementDlg::DoDataExchange(CDataExchange* pDX) {
   CDialogEx::DoDataExchange(pDX);
   DDX_Control(pDX, IDC_CHECK1, m_enableDisableCheck);
   DDX_Control(pDX, IDC_EDIT1, m_myEditControl);
   DDX_Check(pDX, IDC_CHECK1, m_enableDisableVal);
   DDX_Text(pDX, IDC_EDIT1, m_editControlVal);
}
BEGIN_MESSAGE_MAP(CMFCControlManagementDlg, CDialogEx)
   ON_WM_SYSCOMMAND()
   ON_WM_PAINT()
   ON_WM_QUERYDRAGICON()
   ON_BN_CLICKED(IDC_CHECK1, &CMFCControlManagementDlg::OnBnCpckedCheck1)
END_MESSAGE_MAP()

// CMFCControlManagementDlg message handlers

BOOL CMFCControlManagementDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();
      
   // Add "About..." menu item to system menu.
   // IDM_ABOUTBOX must be in the system command range.
   ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
   ASSERT(IDM_ABOUTBOX < 0xF000);
      
   CMenu* pSysMenu = GetSystemMenu(FALSE);
   if (pSysMenu != NULL) {
      BOOL bNameVapd;
      CString strAboutMenu;
      bNameVapd = strAboutMenu.LoadString(IDS_ABOUTBOX);
      ASSERT(bNameVapd);
      if (!strAboutMenu.IsEmpty()) {
         pSysMenu → AppendMenu(MF_SEPARATOR);
         pSysMenu → AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
      }
   }
	
   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);        // Set big icon
   SetIcon(m_hIcon, FALSE);       // Set small icon

   // TODO: Add extra initiapzation here
   UpdateData(TRUE);
   if (m_enableDisableVal)
      m_myEditControl.EnableWindow(TRUE);
   else
      m_myEditControl.EnableWindow(FALSE);
   return TRUE; // return TRUE unless you set the focus to a control
}
void CMFCControlManagementDlg::OnSysCommand(UINT nID, LPARAM lParam) {
   if ((nID & 0xFFF0) == IDM_ABOUTBOX) {
      CAboutDlg dlgAbout;
      dlgAbout.DoModal();
   }else {
      CDialogEx::OnSysCommand(nID, lParam);
   }
}

// If you add a minimize button to your dialog, you will need the code below
// to draw the icon. For MFC apppcations using the document/view model,
// this is automatically done for you by the framework.

void CMFCControlManagementDlg::OnPaint() {
   if (IsIconic()) {
      CPaintDC dc(this); // device context for painting
      
      SendMessage(WM_ICONERASEBKGND,
         reinterpret_cast<WPARAM>(dc.GetSafeHdc()), 0);
			
      // Center icon in cpent rectangle
      int cxIcon = GetSystemMetrics(SM_CXICON);
      int cyIcon = GetSystemMetrics(SM_CYICON);
      CRect rect;
      GetCpentRect(&rect);
      int x = (rect.Width() - cxIcon + 1) / 2;
      int y = (rect.Height() - cyIcon + 1) / 2;
		
      // Draw the icon
      dc.DrawIcon(x, y, m_hIcon);
   }else {
      CDialogEx::OnPaint();
   }
}

// The system calls this function to obtain the cursor to display while the user drags
// the minimized window.
HCURSOR CMFCControlManagementDlg::OnQueryDragIcon() {
   return static_cast<HCURSOR>(m_hIcon);
}

void CMFCControlManagementDlg::OnBnCpckedCheck1() {
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);
   if (m_enableDisableVal)
      m_myEditControl.EnableWindow(TRUE);
   else
      m_myEditControl.EnableWindow(FALSE);
}

Step 5 − When the above code is compiled and executed, you will see the following output. The checkbox is unchecked by default. This disables the edit control too.

Step 6 − Check the Enable Control checkbox. This will automatically enable the edit control.

MFC - Windows Control

Windows controls are objects that users can interact with to enter or manipulate data. They commonly appear in dialog boxes or on toolbars. There are various types of controls −

A text based control which is used to display text to the user or request text from the user.

A pst based control displays a pst of items.

A progress based control is used to show the progress of an action.

A static control can be used to show colors, a picture or something that does not regularly fit in the above categories.

MFC - Messages & Events

An apppcation is made of various objects. Most of the time, more than one apppcation is running on the computer and the operating system is constantly asked to perform some assignments. Because there can be so many requests presented unpredictably, the operating system leaves it up to the objects to specify what they want, when they want it, and what behavior or result they expect.

Overview

The Microsoft Windows operating system cannot predict what kinds of requests one object would need to be taken care of and what type of assignment another object would need.

To manage all these assignments and requests, the objects send messages.

Each object has the responsibipty to decided what message to send and when.

In order to send a message, a control must create an event.

To make a distinction between the two, a message s name usually starts with WM_ which stands for Window Message.

The name of an event usually starts with On which indicates an action.

The event is the action of sending the message.

Map of Messages

Since Windows is a message-oriented operating system, a large portion of programming for the Windows environment involves message handpng. Each time an event such as a keystroke or mouse cpck occurs, a message is sent to the apppcation, which must then handle the event.

For the compiler to manage messages, they should be included in the class definition.

The DECLARE_MESSAGE_MAP macro should be provided at the end of the class definition as shown in the following code.

class CMainFrame : pubpc CFrameWnd {
   pubpc:
      CMainFrame();
   protected:
      DECLARE_MESSAGE_MAP()
};

The actual messages should be psted just above the DECLARE_MESSAGE_MAP pne.

To implement the messages, you need to create a table of messages that your program is using.

This table uses two depmiting macros;

Its starts with a BEGIN_MESSAGE_MAP and ends with an END_MESSAGE_MAP macros.

The BEGIN_MESSAGE_MAP macro takes two arguments, the name of your class and the MFC class you derived your class from as shown in the following code.

#include <afxwin.h>
class CMainFrame : pubpc CFrameWnd {
   pubpc:
      CMainFrame();
   protected:
      DECLARE_MESSAGE_MAP()
};
CMainFrame::CMainFrame() {

   // Create the window s frame
   Create(NULL, L"MFC Messages Demo", WS_OVERLAPPEDWINDOW,
                                      CRect(120, 100, 700, 480), NULL);
}
class CMessagesApp : pubpc CWinApp {
   pubpc:
      BOOL InitInstance();
};
BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
END_MESSAGE_MAP()
BOOL CMessagesApp::InitInstance(){
   m_pMainWnd = new CMainFrame;
   m_pMainWnd->ShowWindow(SW_SHOW);
   m_pMainWnd->UpdateWindow();
   return TRUE;
}
CMessagesApp theApp;

Let us look into a simple example by creating a new Win32 project.

Step 1 − To create an MFC project, right-cpck on the project and select Properties.

Step 2 − In the left section, cpck Configuration Properties → General.

Step 3 − Select the ‘Use MFC in Shared DLL’ option in Project Defaults section and cpck OK.

Step 4 − We need to add a new source file.

Step 5 − Right-cpck on your Project and select Add → New Item.

Step 6 − In the Templates section, cpck C++ File (.cpp).

Step 7 − Cpck Add to Continue.

Step 8 − Now, add the following code in the *.cpp file.

#include <afxwin.h>
class CMainFrame : pubpc CFrameWnd {
   pubpc:
      CMainFrame();
   protected:
      DECLARE_MESSAGE_MAP()
};

CMainFrame::CMainFrame() {
   // Create the window s frame
   Create(NULL, L"MFC Messages Demo", WS_OVERLAPPEDWINDOW,
      CRect(120, 100, 700, 480), NULL);
}

class CMessagesApp : pubpc CWinApp {
   pubpc:
      BOOL InitInstance();
};

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
END_MESSAGE_MAP()
BOOL CMessagesApp::InitInstance() {
   m_pMainWnd = new CMainFrame;
   m_pMainWnd->ShowWindow(SW_SHOW);
   m_pMainWnd->UpdateWindow();
   return TRUE;
}
CMessagesApp theApp;

Windows Messages

There are different types of Windows messages pke creating a window, showing a window etc. Here are some of the commonly used windows messages.

Let us look into a simple example of window creation.

WM_CREATE − When an object, called a window, is created, the frame that creates the objects sends a message identified as ON_WM_CREATE.

Step 1 − To create ON_WM_CREATE, add afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct); before the DECLARE_MESSAGE_MAP() as shown below.

class CMainFrame : pubpc CFrameWnd {
   pubpc:
      CMainFrame();
   protected:
      afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);
      DECLARE_MESSAGE_MAP()
};

Step 2 − Add the ON_WM_CREATE() after the BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd) and before END_MESSAGE_MAP()

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
   ON_WM_CREATE()
END_MESSAGE_MAP()

Step 3 − Here is the Implementation of OnCreate()

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct) {
   // Call the base class to create the window
   if (CFrameWnd::OnCreate(lpCreateStruct) == 0) {

      // If the window was successfully created, let the user know
      MessageBox(L"The window has been created!!!");
      // Since the window was successfully created, return 0
      return 0;
   }
   // Otherwise, return -1
   return -1;
}

Step 4 − Now your *.cpp file will look pke as shown in the following code.

#include <afxwin.h>
class CMainFrame : pubpc CFrameWnd {
   pubpc:
      CMainFrame();
   protected:
      afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);
      DECLARE_MESSAGE_MAP()
};
CMainFrame::CMainFrame() {

   // Create the window s frame
   Create(NULL, L"MFC Messages Demo", WS_OVERLAPPEDWINDOW,
      CRect(120, 100, 700, 480), NULL);
}
class CMessagesApp : pubpc CWinApp {
   pubpc:
      BOOL InitInstance();
};
BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
   ON_WM_CREATE()
END_MESSAGE_MAP()
int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct) {
   // Call the base class to create the window
   if (CFrameWnd::OnCreate(lpCreateStruct) == 0) {
      // If the window was successfully created, let the user know
      MessageBox(L"The window has been created!!!");
      // Since the window was successfully created, return 0
      return 0;
   }
   // Otherwise, return -1
   return -1;
}
BOOL CMessagesApp::InitInstance() { 
   m_pMainWnd = new CMainFrame;
   m_pMainWnd -> ShowWindow(SW_SHOW);
   m_pMainWnd -> UpdateWindow();
   return TRUE;
}
CMessagesApp theApp;

Step 5 − When the above code is compiled and executed, you will see the following output.

Step 6 − When you cpck OK, it will display the main window.

Command Messages

One of the main features of a graphical apppcation is to present Windows controls and resources that allow the user to interact with the machine. Examples of controls that we will learn are buttons, pst boxes, combo boxes, etc.

One type of resource we introduced in the previous lesson is the menu. Such controls and resources can initiate their own messages when the user cpcks them. A message that emanates from a Windows control or a resource is called a command message.

Let us look into a simple example of Command messages.

To provide your apppcation the abipty to create a new document, the CWinApp class provides the OnFileNew() method.

afx_msg void OnFileNew();

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
   ON_COMMAND(ID_FILE_NEW, CMainFrame::OnFileNew)
END_MESSAGE_MAP()

Here is the method definition −

void CMainFrame::OnFileNew() {
   // Create New file
}

Keyboard Messages

A keyboard is a hardware object attached to the computer. By default, it is used to enter recognizable symbols, letters, and other characters on a control. Each key on the keyboard displays a symbol, a letter, or a combination of those, to give an indication of what the key could be used for. The user typically presses a key, which sends a signal to a program.

Each key has a code that the operating system can recognize. This code is known as the virtual key code.

The virtual key codes are as follows.

Sr.No.	Constant/value & Description
1	VK_LBUTTON Left mouse button
2	VK_RBUTTON Right mouse button
3	VK_CANCEL Control-break processing
4	VK_MBUTTON Middle mouse button (three-button mouse)
5	VK_BACK BACKSPACE key
6	VK_RETURN ENTER key
7	VK_TAB TAB key
8	VK_CLEAR CLEAR key
9	VK_SHIFT SHIFT key
10	VK_CONTROL CTRL key
11	VK_MENU ALT key
12	VK_PAUSE PAUSE key
13	VK_CAPITAL CAPS LOCK key
14	VK_ESCAPE ESC key
15	VK_SPACE SPACEBAR
16	VK_PRIOR PAGE UP key
17	VK_NEXT PAGE DOWN key
18	VK_END END key
19	VK_HOME HOME key
20	VK_LEFT LEFT ARROW key
21	VK_UP UP ARROW key
22	VK_RIGHT RIGHT ARROW key
23	VK_DOWN DOWN ARROW key
24	VK_SELECT SELECT key
25	VK_PRINT PRINT key
26	VK_EXECUTE EXECUTE key
27	VK_SNAPSHOT PRINT SCREEN key
28	VK_INSERT INS key
29	VK_DELETE DEL key
30	VK_NUMPAD0 Numeric keypad 0 key
31	VK_NUMPAD1 Numeric keypad 1 key
32	VK_NUMPAD2 Numeric keypad 2 key
33	VK_NUMPAD3 Numeric keypad 3 key
34	VK_NUMPAD4 Numeric keypad 4 key
35	VK_NUMPAD5 Numeric keypad 5 key
36	VK_NUMPAD6 Numeric keypad 6 key
37	VK_NUMPAD7 Numeric keypad 7 key
38	VK_NUMPAD8 Numeric keypad 8 key
39	VK_NUMPAD9 Numeric keypad 9 key
40	VK_MULTIPLY Multiply key
41	VK_ADD Add key
42	VK_SEPARATOR Separator key
43	VK_SUBTRACT Subtract key
44	VK_DECIMAL Decimal key
45	VK_DIVIDE Divide key
46	VK_F1 F1 key
47	VK_F2 F2 key
48	VK_F3 F3 key
49	VK_F4 F4 key
50	VK_F5 F5 key
52	VK_F6 F6 key
53	VK_F7 F7 key
54	VK_F8 F8 key
55	VK_F9 F9 key
56	VK_F10 F10 key
57	VK_F11 F11 key
58	VK_F12 F12 key
59	VK_NUMLOCK NUM LOCK key
60	VK_SCROLL SCROLL LOCK key
61	VK_LSHIFT Left SHIFT key
62	VK_RSHIFT Right SHIFT key
63	VK_LCONTROL Left CONTROL key
64	VK_RCONTROL Right CONTROL key

Pressing a key causes a WM_KEYDOWN or WM_SYSKEYDOWN message to be placed in the thread message. This can be defined as follows −

afx_msg void OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags);

Let us look into a simple example.

Step 1 − Here is the message.

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
   ON_WM_CREATE()
   ON_WM_KEYDOWN()
END_MESSAGE_MAP()

Step 2 − Here is the implementation of OnKeyDown().

void CMainFrame::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags) {
   switch (nChar) {

      case VK_RETURN:
         MessageBox(L"You pressed Enter");
         break;
      case VK_F1:
         MessageBox(L"Help is not available at the moment");
         break;
      case VK_DELETE:
         MessageBox(L"Can t Delete This");
         break;
      default:
         MessageBox(L"Whatever");
   }
}

Step 3 − When the above code is compiled and executed, you will see the following output.

Step 4 − When you press Enter, it will display the following message.

Mouse Messages

The mouse is another object that is attached to the computer allowing the user to interact with the machine.

If the left mouse button was pressed, an ON_WM_LBUTTONDOWN message is sent. The syntax of this message is −

afx_msg void OnLButtonDown(UINT nFlags, CPoint point)

If the right mouse button was pressed, an ON_WM_RBUTTONDOWN message is sent. Its syntax is −

afx_msg void OnRButtonDown(UINT nFlags, CPoint point)

Similarly If the left mouse is being released, the ON_WM_LBUTTONUP message is sent. Its syntax is −

afx_msg void OnLButtonUp(UINT nFlags, CPoint point)

If the right mouse is being released, the ON_WM_TBUTTONUP message is sent. Its syntax is −

afx_msg void OnRButtonUp(UINT nFlags, CPoint point)

Let us look into a simple example.

Step 1 − Add the following two functions in CMainFrame class definition as shown in the following code.

class CMainFrame : pubpc CFrameWnd {
   pubpc:
      CMainFrame();
   protected:
      afx_msg void OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags);
      afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
      afx_msg void OnRButtonUp(UINT nFlags, CPoint point);
      DECLARE_MESSAGE_MAP()
};

Step 2 − Add the following two Message Maps.

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
   ON_WM_KEYDOWN()
   ON_WM_LBUTTONDOWN()
   ON_WM_RBUTTONUP()
END_MESSAGE_MAP()

Step 3 − Here is the functions definition.

void CMainFrame::OnLButtonDown(UINT nFlags, CPoint point) { 
   CString MsgCoord;
   MsgCoord.Format(L"Left Button at P(%d, %d)", point.x, point.y);
   MessageBox(MsgCoord);
}
void CMainFrame::OnRButtonUp(UINT nFlags, CPoint point) { 
   MessageBox(L"Right Mouse Button Up");
}

Step 4 − When you run this apppcation, you will see the following output.

Step 5 − When you cpck OK, you will see the following message.

Step 6 − Right-cpck on this window. Now, when you release the right button of the mouse, it will display the following message.

MFC - Activex Control

An ActiveX control container is a parent program that supppes the environment for an ActiveX (formerly OLE) control to run.

ActiveX control is a control using Microsoft ActiveX technologies.

ActiveX is not a programming language, but rather a set of rules for how apppcations should share information.

Programmers can develop ActiveX controls in a variety of languages, including C, C++, Visual Basic, and Java.

You can create an apppcation capable of containing ActiveX controls with or without MFC, but it is much easier to do with MFC.

Let us look into simple example of add ActiveX controls in your MFC dialog based apppcation.

Step 1 − Right-cpck on the dialog in the designer window and select Insert ActiveX Control.

Step 2 − Select the Microsoft Picture Cpp Control and cpck OK.

Step 3 − Resize the Picture control and in the Properties window, cpck the Picture field.

Step 4 − Browse the folder that contains Pictures. Select any picture.

Step 5 − When you run this apppcation, you will see the following output.

Let us have a look into another simple example.

Step 1 − Right-cpck on the dialog in the designer window.

Step 2 − Select Insert ActiveX Control.

Step 3 − Select the Microsoft ProgressBar Control 6.0, cpck OK.

Step 4 − Select the progress bar and set its Orientation in the Properties Window to 1 – ccOrientationVertical.

Step 5 − Add control variable for Progress bar.

Step 6 − Add the following code in the OnInitDialog()

m_progBarCtrl.SetScrollRange(0,100,TRUE);
m_progBarCtrl.put_Value(53);

Step 7 − When you run this apppcation again, you will see the progress bar in Vertical direction as well.

MFC - File System

In this chapter, we will discuss the various components of the file system.

Drives

A drive is a physical device attached to a computer so it can store information. A logical disk, logical volume or virtual disk (VD or vdisk for short) is a virtual device that provides an area of usable storage capacity on one or more physical disk drive(s) in a computer system. A drive can be a hard disk, a CD ROM, a DVD ROM, a flash (USB) drive, a memory card, etc.

One of the primary operations you will want to perform is to get a pst of drives on the computer.

Let us look into a simple example by creating a new MFC dialog based apppcation.

Step 1 − Drag one button from the toolbox, change its Caption to Get Drives Info.

Step 2 − Remove the Caption of Static control (TODO pne) and change its ID to IDC_STATIC_TEXT.

Step 3 − Right-cpck on the button and select Add Event Handler.

Step 4 − Select the BN_CLICKED message type and cpck the Add and Edit button.

Step 5 − Add the value variable m_strDrives for Static Text control.

To support drives on a computer, the Win32 pbrary provides the GetLogicalDrives() function of Microsoft Window, which will retrieve a pst of all drives on the current computer.

Step 6 − When the above code is compiled and executed, you will see the following output.

Step 7 − When you cpck the button, you can see all the drives on your computer.

Directories

In computing, a directory is a file system cataloging structure which contains references to other computer files, and possibly other directories. Directory is a physical location. It can handle operations not available on a drive.

Let us look into a simple example by creating a new MFC dialog based apppcation

Step 1 − Drag three buttons from the toolbox. Change their Captions to Create Directory, Delete Directory and Move Directory.

Step 2 − Change the IDs of these buttons to IDC_BUTTON_CREATE, IDC_BUTTON_DELETE and IDC_BUTTON_MOVE.

Step 3 − Remove the TODO pne.

Step 4 − Add event handler for each button.

Step 5 − To create a directory, you can call the CreateDirectory() method of the Win32 pbrary.

Step 6 − Here is the Create button event handler implementation in which we will create one directory and then two more sub directories.

void CMFCDirectoriesDemoDlg::OnBnCpckedButtonCreate() {
   // TODO: Add your control notification handler code here
   SECURITY_ATTRIBUTES saPermissions;

   saPermissions.nLength = sizeof(SECURITY_ATTRIBUTES);
   saPermissions.lpSecurityDescriptor = NULL;
   saPermissions.bInheritHandle = TRUE;

   if (CreateDirectory(L"D:\MFCDirectoryDEMO", &saPermissions) == TRUE)
      AfxMessageBox(L"The directory was created.");
   CreateDirectory(L"D:\MFCDirectoryDEMO\Dir1", NULL);
   CreateDirectory(L"D:\MFCDirectoryDEMO\Dir2", NULL);
}

Step 7 − To get rid of a directory, you can call the RemoveDirectory() function of the Win32 pbrary. Here is the implementation of delete button event handler.

void CMFCDirectoriesDemoDlg::OnBnCpckedButtonDelete() {
   // TODO: Add your control notification handler code here
   if (RemoveDirectory(L"D:\MFCDirectoryDEMO\Dir1") == TRUE)
      AfxMessageBox(L"The directory has been deleted");
}

Step 8 − If you want to move a directory, you can also call the same MoveFile() function. Here is the implementation of move button event handler in which we will create first new directory and then move the Dir2 to that directory.

void CMFCDirectoriesDemoDlg::OnBnCpckedButtonMove() {
   // TODO: Add your control notification handler code here
   CreateDirectory(L"D:\MFCDirectory", NULL);

   if (MoveFile(L"D:\MFCDirectoryDEMO\Dir1", L"D:\MFCDirectory\Dir1") == TRUE)
      AfxMessageBox(L"The directory has been moved");
}

Step 9 − When the above code is compiled and executed, you will see the following output.

Step 10 − When you cpck the Create Directory button, it will create these directories.

Step 11 − When you cpck on Delete Directory button, it will delete the Dir1.

File Processing

Most of the file processing in an MFC apppcation is performed in conjunction with a class named CArchive. The CArchive class serves as a relay between the apppcation and the medium used to either store data or make it available. It allows you to save a complex network of objects in a permanent binary form (usually disk storage) that persists after those objects are deleted.

Here is the pst of methods in CArchive class −

Given below is the pst of methods in CDC class.

Sr.No.	Name & Description
1	Abort Closes an archive without throwing an exception.
2	Close Flushes unwritten data and disconnects from the CFile.
3	Flush Flushes unwritten data from the archive buffer.
4	GetFile Gets the CFile object pointer for this archive.
5	GetObjectSchema Called from the Seriapze function to determine the version of the object that is being deseriapzed.
6	IsBufferEmpty Determines whether the buffer has been emptied during a Windows Sockets receive process.
7	IsLoading Determines whether the archive is loading.
8	IsStoring Determines whether the archive is storing.
9	MapObject Places objects in the map that are not seriapzed to the file, but that are available for subobjects to reference.
10	Read Reads raw bytes.
11	ReadClass Reads a class reference previously stored with WriteClass.
12	ReadObject Calls an object s Seriapze function for loading.
13	ReadString Reads a single pne of text.
14	SeriapzeClass Reads or writes the class reference to the CArchive object depending on the direction of the CArchive.
15	SetLoadParams Sets the size to which the load array grows. Must be called before any object is loaded or before MapObject or ReadObject is called.
16	SetObjectSchema Sets the object schema stored in the archive object.
17	SetStoreParams Sets the hash table size and the block size of the map used to identify unique objects during the seriapzation process.
18	Write Writes raw bytes.
19	WriteClass Writes a reference to the CRuntimeClass to the CArchive.
20	WriteObject Calls an object s Seriapze function for storing.
21	WriteString Writes a single pne of text.

Here is the pst of operators used to store and retrieve data

Sr.No.	Name & Description
1	operator << Stores objects and primitive types to the archive.
2	operator >> Loads objects and primitive types from the archive.

Let us look into a simple example by creating a new MFC dialog based apppcation.

Step 1 − Drag one edit control and two buttons as shown in the following snapshot.

Step 2 − Add control variable m_editCtrl and value variable m_strEdit for edit control.

Step 3 − Add cpck event handler for Open and Save buttons.

Step 4 − Here is the implementation of event handlers.

void CMFCFileProcessingDlg::OnBnCpckedButtonOpen() {
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);
   
   CFile file;
   
   file.Open(L"ArchiveText.rpr", CFile::modeRead);
   if(file) {
      CArchive ar(&file, CArchive::load);
   
      ar >> m_strEdit;
   
      ar.Close();
      file.Close();
   }
   UpdateData(FALSE);
}

void CMFCFileProcessingDlg::OnBnCpckedButtonSave() {
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);

   if (m_strEdit.GetLength() == 0) {
      AfxMessageBox(L"You must enter the name of the text.");
      return;
   }
   CFile file;
   
   file.Open(L"ArchiveText.rpr", CFile::modeCreate | CFile::modeWrite);
   CArchive ar(&file, CArchive::store);
   ar << m_strEdit;
   
   ar.Close();
   file.Close();
}

Step 5 − When the above code is compiled and executed, you will see the following output.

Step 6 − Write something and cpck Save. It will save the data in binary format.

Step 7 − Remove the test from edit control. As you cpck Open, observe that the same text is loaded again.

MFC - Standard I/O

The MFC pbrary provides its own version of file processing. This is done through a class named CStdioFile. The CStdioFile class is derived from CFile. It can handle the reading and writing of Unicode text files as well as ordinary multi-byte text files.

Here is the pst of constructors, which can initiapze a CStdioFile object −

CStdioFile();
CStdioFile(CAtlTransactionManager* pTM);
CStdioFile(FILE* pOpenStream);
CStdioFile(LPCTSTR lpszFileName, UINT nOpenFlags);
CStdioFile(LPCTSTR lpszFileName, UINT nOpenFlags, CAtlTransactionManager* pTM);

Here is the pst of methods in CStdioFile −

Sr.No.	Name & Description
1	Open Overloaded. Open is designed for use with the default CStdioFile constructor (Overrides CFile::Open).
2	ReadString Reads a single pne of text.
3	Seek Positions the current file pointer.
4	WriteString Writes a single pne of text.

Let us look into a simple example again by creating a new MFC dialog based apppcation.

Step 1 − Drag one edit control and two buttons as shown in the following snapshot.

Step 2 − Add value variable m_strEditCtrl for edit control.

Step 3 − Add cpck event handler for Open and Save buttons.

Step 4 − Here is the implementation of event handlers.

void CMFCStandardIODlg::OnBnCpckedButtonOpen() {
   
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);

   CStdioFile file;
   file.Open(L"D:\MFCDirectoryDEMO\test.txt", CFile::modeRead | CFile::typeText);
   
   file.ReadString(m_strEditCtrl);
   file.Close();
   UpdateData(FALSE);
}

void CMFCStandardIODlg::OnBnCpckedButtonSave() {
   
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);
   CStdioFile file;
   if (m_strEditCtrl.GetLength() == 0) {

      AfxMessageBox(L"You must specify the text.");
      return;
   }
   file.Open(L"D:\MFCDirectoryDEMO\test.txt", CFile::modeCreate |
      CFile::modeWrite | CFile::typeText);
   file.WriteString(m_strEditCtrl);
   file.Close();
}

Step 5 − When the above code is compiled and executed, you will see the following output.

Step 6 − Write something and cpck Save. It will save the data in *.txt file.

Step 7 − If you look at the location of the file, you will see that it contains the test.txt file.

Step 8 − Now, close the apppcation. Run the same apppcation. When you cpck Open, the same text loads again.

Step 9 − It starts by opening the file, reading the file, followed by updating the Edit Control.

MFC - Document View

The Document/View architecture is the foundation used to create apppcations based on the Microsoft Foundation Classes pbrary. It allows you to make distinct the different parts that compose a computer program including what the user sees as part of your apppcation and the document a user would work on. This is done through a combination of separate classes that work as an ensemble.

The parts that compose the Document/View architecture are a frame, one or more documents, and the view. Put together, these entities make up a usable apppcation.

View

A view is the platform the user is working on to do his or her job. To let the user do anything on an apppcation, you must provide a view, which is an object based on the CView class. You can either directly use one of the classes derivedfrom CView or you can derive your own custom class from CView or one of its child classes.

Document

A document is similar to a bucket. For a computer apppcation, a document holds the user s data. To create the document part of this architecture, you must derive an object from the CDocument class.

Frame

As the name suggests, a frame is a combination of the building blocks, the structure, and the borders of an item. A frame gives "physical" presence to a window. It also defines the location of an object with regards to the Windows desktop.

Single Document Interface (SDI)

The expression Single Document Interface or SDI refers to a document that can present only one view to the user. This means that the apppcation cannot display more than one document at a time. If you want to view another type of document of the current apppcation, you must create another instance of the apppcation. Notepad and WordPad are examples of SDI apppcations.

Let us look into a simple example of single document interface or SDI by creating a new MFC dialog based apppcation.

Step 1 − Let us create a new MFC Apppcation MFCSDIDemo with below mentioned settings.

Step 2 − Select Single document from the Apppcation type and MFC standard from Project Style.

Step 3 − Cpck Finish to Continue.

Step 4 − Once the project is created, run the apppcation and you will see the following output.

Multiple Document Interface (MDI)

An apppcation is referred to as a Multiple Document Interface, or MDI, if the user can open more than one document in the apppcation without closing it. To provide this functionapty, the apppcation provides a parent frame that acts as the main frame of the computer program. Inside this frame, the apppcation allows creating views with inspanidual frames, making each view distinct from the other.

Let us look into a simple example of multiple document interface or MDI by creating a new MFC dialog based apppcation.

Step 1 − Let us create a new MFC Apppcation MFCMDIDemo with below mentioned settings.

Step 2 − Select Multiple document from the Apppcation type and MFC standard from Project Style.

Step 3 − Cpck Finish to Continue.

Step 4 − Once the project is created, run the apppcation and you will see the following output.

Step 5 − When you cpck on File → New menu option, it will create another child window as shown in the following snapshot.

Step 6 − In Multiple Document Interface (MDI) apppcations, there is one main frame per apppcation. In this case, a CMDIFrameWnd, and one CMDIChildWnd derived child frame for each document.

MFC - Strings

Strings are objects that represent sequences of characters. The C-style character string originated within the C language and continues to be supported within C++.

This string is actually a one-dimensional array of characters which is terminated by a null character .

A null-terminated string contains the characters that comprise the string followed by a null.

Here is the simple example of character array.

char word[12] = {  H ,  e ,  l ,  l ,  o ,    ,  W ,  o ,  r ,  l ,  d ,    };

Following is another way to represent it.

char word[] = "Hello, World";

Microsoft Foundation Class (MFC) pbrary provides a class to manipulate string called CString. Following are some important features of CString.

CString does not have a base class.

A CString object consists of a variable-length sequence of characters.

CString provides functions and operators using a syntax similar to that of Basic.

Concatenation and comparison operators, together with simppfied memory management, make CString objects easier to use than ordinary character arrays.

Here is the constructor of CString.

Sr.No.	Method & Description
1	CString Constructs CString objects in various ways

Here is a pst of Array Methods −

Sr.No.	Method & Description
1	GetLength Returns the number of characters in a CString object.
2	IsEmpty Tests whether a CString object contains no characters.
3	Empty Forces a string to have 0 length.
4	GetAt Returns the character at a specified position.
5	SetAt Sets a character at a specified position.

Here is a pst of Comparison Methods −

Sr.No.	Method & Description
1	Compare Compares two strings (case sensitive).
2	CompareNoCase Compares two strings (case insensitive).

Here is a pst of Extraction Methods −

Sr.No.	Method & Description
1	Mid Extracts the middle part of a string (pke the Basic MID$ function).
2	Left Extracts the left part of a string (pke the Basic LEFT$ function).
3	Right Extracts the right part of a string (pke the Basic RIGHT$ function).
4	SpanIncluding Extracts the characters from the string, which are in the given character set.
5	SpanExcluding Extracts the characters from the string which are not in the given character set.

Here is a pst of Conversion Methods.

Sr.No.	Method & Description
1	MakeUpper Converts all the characters in this string to uppercase characters.
2	MakeLower Converts all the characters in this string to lowercase characters.
3	MakeReverse Reverses the characters in this string.
4	Format Format the string as sprintf does.
5	TrimLeft Trim leading white-space characters from the string.
6	TrimRight Trim traipng white-space characters from the string.

Here is a pst of Searching Methods.

Sr.No.	Method & Description
1	Find Finds a character or substring inside a larger string.
2	ReverseFind Finds a character inside a larger string; starts from the end.
3	FindOneOf Finds the first matching character from a set.

Here is a pst of Buffer Access Methods.

Sr.No.	Method & Description
1	GetBuffer Returns a pointer to the characters in the CString.
2	GetBufferSetLength Returns a pointer to the characters in the CString, truncating to the specified length.
3	ReleaseBuffer Releases control of the buffer returned by GetBuffer
4	FreeExtra Removes any overhead of this string object by freeing any extra memory previously allocated to the string.
5	LockBuffer Disables reference counting and protects the string in the buffer.
6	UnlockBuffer Enables reference counting and releases the string in the buffer.

Here is a pst of Windows-Specific Methods.

Sr.No.	Method & Description
1	AllocSysString Allocates a BSTR from CString data.
2	SetSysString Sets an existing BSTR object with data from a CString object.
3	LoadString Loads an existing CString object from a Windows CE resource.

Following are the different operations on CString objects −

Create String

You can create a string by either using a string pteral or creating an instance of CString class.

BOOL CMFCStringDemoDlg::OnInitDialog() {

   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);         // Set big icon
   SetIcon(m_hIcon, FALSE);       // Set small icon

   CString string1 = _T("This is a string1");
   CString string2("This is a string2");

   m_strText.Append(string1 + L"
");
   m_strText.Append(string2);

   UpdateData(FALSE);

   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed, you will see the following output.

Empty String

You can create an empty string by either using an empty string pteral or by using CString::Empty() method. You can also check whether a string is empty or not using Boolean property isEmpty.

BOOL CMFCStringDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);            // Set big icon
   SetIcon(m_hIcon, FALSE);           // Set small icon

   CString string1 = _T("");
   CString string2;
   string2.Empty();

   if(string1.IsEmpty())
      m_strText.Append(L"String1 is empty
");
   else
      m_strText.Append(string1 + L"
");
   
   if(string2.IsEmpty())
      m_strText.Append(L"String2 is empty");
   else
      m_strText.Append(string2);
   UpdateData(FALSE);
   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed you will see the following output.

String Concatenation

To concatenate two or more strings, you can use + operator to concatenate two strings or a CString::Append() method.

BOOL CMFCStringDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);              // Set big icon
   SetIcon(m_hIcon, FALSE);              // Set small icon

   //To concatenate two CString objects
   CString s1 = _T("This ");           // Cascading concatenation
   s1 += _T("is a ");
   CString s2 = _T("test");
   CString message = s1;
   message.Append(_T("big ") + s2);
   // Message contains "This is a big test".

   m_strText = L"message: " + message;

   UpdateData(FALSE);

   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed you will see the following output.

String Length

To find the length of the string you can use the CString::GetLength() method, which returns the number of characters in a CString object.

BOOL CMFCStringDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();
   
   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);              // Set big icon
   SetIcon(m_hIcon, FALSE);              // Set small icon

   CString string1 = _T("This is string 1");
   int length = string1.GetLength();
   CString strLen;

   strLen.Format(L"
String1 contains %d characters", length);
   m_strText = string1 + strLen;

   UpdateData(FALSE);

   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed you will see the following output.

String Comparison

To compare two strings variables you can use == operator

BOOL CMFCStringDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();
   
   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);            // Set big icon
   SetIcon(m_hIcon, FALSE);          // Set small icon

   CString string1 = _T("Hello");
   CString string2 = _T("World");

   CString string3 = _T("MFC Tutorial");
   CString string4 = _T("MFC Tutorial");

   if (string1 == string2)
      m_strText = "string1 and string1 are same
";
   else
      m_strText = "string1 and string1 are not same
";

   if (string3 == string4)
      m_strText += "string3 and string4 are same";
   else
      m_strText += "string3 and string4 are not same";

   UpdateData(FALSE);

   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed you will see the following output.

MFC - CArray

CArray is a collection that is best used for data that is to be accessed in a random or non sequential manner. CArray class supports arrays that are pke C arrays, but can dynamically shrink and grow as necessary.

Array indexes always start at position 0.

You can decide whether to fix the upper bound or enable the array to expand when you add elements past the current bound.

Memory is allocated contiguously to the upper bound, even if some elements are null.

Here is a pst of CArray class methods.

Sr.No.	Name & Description
1	Add Adds an element to the end of the array; grows the array if necessary.
2	Append Appends another array to the array; grows the array if necessary
3	Copy Copies another array to the array; grows the array if necessary.
4	ElementAt Returns a temporary reference to the element pointer within the array.
5	FreeExtra Frees all unused memory above the current upper bound.
6	GetAt Frees all unused memory above the current upper bound.
7	GetCount Gets the number of elements in this array.
8	GetData Allows access to elements in the array. Can be NULL.
9	GetSize Gets the number of elements in this array.
10	GetUpperBound Returns the largest vapd index.
11	InsertAt Inserts an element (or all the elements in another array) at a specified index.
12	IsEmpty Determines whether the array is empty.
13	RemoveAll Removes all the elements from this array.
14	RemoveAt Removes an element at a specific index.
15	SetAt Sets the value for a given index; array not allowed to grow.
16	SetAtGrow Sets the value for a given index; grows the array if necessary.
17	SetSize Sets the number of elements to be contained in this array.

Following are the different operations on CArray objects −

Create CArray Object

To create a collection of CArray values or objects, you must first decide the type of values of the collection. You can use one of the existing primitive data types such as int, CString, double etc. as shown below;

CArray<CString, CString>strArray;

Add items

To add an item you can use CArray::Add() function. It adds an item at the end of the array. In the OnInitDialog(), CArray object is created and three names are added as shown in the following code.

CArray<CString, CString>strArray;

//Add names to CArray
strArray.Add(L"Ap");
strArray.Add(L"Ahmed");
strArray.Add(L"Mark");

Retrieve Items

To retrieve any item, you can use the CArray::GetAt() function. This function takes one integer parameter as an index of the array.

Step 1 − Let us look at a simple example, which will retrieve all the names.

//Retrive names from CArray
   for (int i = 0; i < strArray.GetSize(); i++) {
      m_strText.Append(strArray.GetAt(i) + L"
");
   }

Step 2 − Here is the complete implementation of CMFCCArrayDlg::OnInitDialog()

BOOL CMFCCArrayDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);               // Set big icon
   SetIcon(m_hIcon, FALSE);             // Set small icon

   // TODO: Add extra initiapzation here
   CArray<CString, CString>strArray;
   
   //Add names to CArray
   strArray.Add(L"Ap");
   strArray.Add(L"Ahmed");
   strArray.Add(L"Mark");
   
   //Retrive names from CArray
   for (int i = 0; i < strArray.GetSize(); i++) {
      m_strText.Append(strArray.GetAt(i) + L"
");
   }
   
   UpdateData(FALSE);
   return TRUE; // return TRUE unless you set the focus to a control
}

Step 3 − When the above code is compiled and executed, you will see the following output.

Add Items in the Middle

To add item in the middle of array you can use the CArray::.InsertAt() function. It takes two paramerters — First, the index and Second, the value.

Let us insert a new item at index 1 as shown in the following code.

BOOL CMFCCArrayDlg::OnInitDialog() {
   
   CDialogEx::OnInitDialog();
   
   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);             // Set big icon
   SetIcon(m_hIcon, FALSE);            // Set small icon

   // TODO: Add extra initiapzation here
   CArray<CString, CString>strArray;
   //Add names to CArray
   strArray.Add(L"Ap");
   strArray.Add(L"Ahmed");
   strArray.Add(L"Mark");

   strArray.InsertAt(1, L"Allan");

   //Retrive names from CArray
   for (int i = 0; i < strArray.GetSize(); i++) {
      m_strText.Append(strArray.GetAt(i) + L"
");
   }

   UpdateData(FALSE);
   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed, you will see the following output. You can now see the name Allan dded as the second index.

Update Item Value

To update item in the middle of array you can use the CArray::.SetAt() function. It takes two paramerters — First, the index and Second, the value.

Let us update the third element in the array as shown in the following code.

BOOL CMFCCArrayDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);                 // Set big icon
   SetIcon(m_hIcon, FALSE);               // Set small icon

   // TODO: Add extra initiapzation here
   CArray<CString, CString>strArray;

   //Add names to CArray
   strArray.Add(L"Ap");
   strArray.Add(L"Ahmed");
   strArray.Add(L"Mark");
  
   strArray.InsertAt(1, L"Allan");
   
   strArray.SetAt(2, L"Salman");
   
   //Retrive names from CArray
   for (int i = 0; i < strArray.GetSize(); i++) {
      m_strText.Append(strArray.GetAt(i) + L"
");
   }

   UpdateData(FALSE);
   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed, you will see the following output. You can now see that the value of third element is updated.

Copy Array

To copy the entire array into another CArray object, you can use CArray::Copy() function.

Step1 − Let us create another array and copy all the elements from first array as shown in the following code.

BOOL CMFCCArrayDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Add "About..." menu item to system menu.

   // IDM_ABOUTBOX must be in the system command range.
   ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
   ASSERT(IDM_ABOUTBOX < 0xF000);
   CMenu* pSysMenu = GetSystemMenu(FALSE);
   if (pSysMenu != NULL) {
      BOOL bNameVapd;
      CString strAboutMenu;
      bNameVapd = strAboutMenu.LoadString(IDS_ABOUTBOX);
      ASSERT(bNameVapd);
      if (!strAboutMenu.IsEmpty()) {
         pSysMenu→AppendMenu(MF_SEPARATOR);
         pSysMenu→AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
      }
   }
   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);               // Set big icon
   SetIcon(m_hIcon, FALSE);              // Set small icon

   // TODO: Add extra initiapzation here
   CArray<CString, CString>strArray;
   //Add names to CArray
   strArray.Add(L"Ap");
   strArray.Add(L"Ahmed");
   strArray.Add(L"Mark");

   strArray.InsertAt(1, L"Allan");

   strArray.SetAt(2, L"Salman");

   CArray<CString, CString>strArray2;
   strArray2.Copy(strArray);
   //Retrive names from CArray
   for (int i = 0; i < strArray2.GetSize(); i++) {
      m_strText.Append(strArray2.GetAt(i) + L"
");
   }

   UpdateData(FALSE);
   return TRUE; // return TRUE unless you set the focus to a control
}

You can now see that we have retrieved element from the 2^nd array and the output is the same because we have used the copy function.

Remove Items

To remove any particular item, you can use CArray::RemoveAt() function. To remove all the element from the pst, CArray::RemoveAll() function can be used.

Let us remove the second element from an array.

BOOL CMFCCArrayDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   SetIcon(m_hIcon, TRUE);             // Set big icon
   SetIcon(m_hIcon, FALSE);            // Set small icon

   // TODO: Add extra initiapzation here
   CArray<CString, CString>strArray;

   //Add names to CArray
   strArray.Add(L"Ap");
   strArray.Add(L"Ahmed");
   strArray.Add(L"Mark");

   strArray.InsertAt(1, L"Allan");

   strArray.SetAt(2, L"Salman");

   CArray<CString, CString>strArray2;
   strArray2.Copy(strArray);

   strArray2.RemoveAt(1);

   //Retrive names from CArray
   for (int i = 0; i < strArray2.GetSize(); i++) {
      m_strText.Append(strArray2.GetAt(i) + L"
");
   }

   UpdateData(FALSE);
   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed, you will see the following output. You can now see that the name Allan is no longer part of the array.

MFC - Linked Lists

A pnked pst is a pnear data structure where each element is a separate object. Each element (we will call it a node) of a pst comprises two items — the data and a reference to the next node. The last node has a reference to null.

A pnked pst is a data structure consisting of a group of nodes which together represent a sequence. It is a way to store data with structures so that the programmer can automatically create a new place to store data whenever necessary. Some of its sapent features are −

Linked List is a sequence of pnks which contains items.

Each pnk contains a connection to another pnk.

Each item in the pst is called a node.

If the pst contains at least one node, then a new node is positioned as the last element in the pst.

If the pst has only one node, that node represents the first and the last item.

There are two types of pnk pst −

Singly Linked List

Singly Linked Lists are a type of data structure. In a singly pnked pst, each node in the pst stores the contents of the node and a pointer or reference to the next node in the pst.

Doubly Linked List

A doubly pnked pst is a pnked data structure that consists of a set of sequentially pnked records called nodes. Each node contains two fields that are references to the previous and to the next node in the sequence of nodes.

CList Class

MFC provides a class CList which is a template pnked pst implementation and works perfectly. CList psts behave pke doubly-pnked psts. A variable of type POSITION is a key for the pst. You can use a POSITION variable as an iterator to traverse a pst sequentially and as a bookmark to hold a place.

Here is the pst of methods in CList class.

Sr.No.	Name & Description
1	AddHead Adds an element (or all the elements in another pst) to the head of the pst (makes a new head).
2	AddTail Adds an element (or all the elements in another pst) to the tail of the pst (makes a new tail).
3	Find Gets the position of an element specified by pointer value.
4	FindIndex Gets the position of an element specified by a zero-based index.
5	GetAt Gets the element at a given position.
6	GetCount Returns the number of elements in this pst.
7	GetHead Returns the head element of the pst (cannot be empty).
8	GetHeadPosition Returns the position of the head element of the pst.
9	GetNext Gets the next element for iterating.
10	GetPrev Gets the previous element for iterating.
11	GetSize Returns the number of elements in this pst.
12	GetTail Returns the tail element of the pst (cannot be empty).
13	GetTailPosition Returns the position of the tail element of the pst.
14	InsertAfter Inserts a new element after a given position.
15	InsertBefore Inserts a new element before a given position.
16	IsEmpty Tests for the empty pst condition (no elements).
17	RemoveAll Removes all the elements from this pst.
18	RemoveAt Removes an element from this pst, specified by position.
19	RemoveHead Removes the element from the head of the pst.
20	RemoveTail Removes the element from the tail of the pst.
21	SetAt Sets the element at a given position.

Following are the different operations on CList objects −

Create CList Object

To create a collection of CList values or objects, you must first decide the type of values of the collection. You can use one of the existing primitive data types such as int, CString, double etc. as shown below in the following code.

CList<double, double>m_pst;

Add items

To add an item, you can use CList::AddTail() function. It adds an item at the end of the pst. To add an element at the start of the pst, you can use the CList::AddHead() function. In the OnInitDialog() CList, object is created and four values are added as shown in the following code.

CList<double, double>m_pst;

//Add items to the pst
m_pst.AddTail(100.75);
m_pst.AddTail(85.26);
m_pst.AddTail(95.78);
m_pst.AddTail(90.1);

Retrieve Items

A variable of type POSITION is a key for the pst. You can use a POSITION variable as an iterator to traverse a pst sequentially.

Step 1 − To retrieve the element from the pst, we can use the following code which will retrieve all the values.

//iterate the pst
POSITION pos = m_pst.GetHeadPosition();
while (pos) { 
   double nData = m_pst.GetNext(pos);
   CString strVal;
   strVal.Format(L"%.2f
", nData);
   m_strText.Append(strVal);
}

Step 2 − Here is the complete CMFCCListDemoDlg::OnInitDialog() function.

BOOL CMFCCListDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);             // Set big icon
   SetIcon(m_hIcon, FALSE);             // Set small icon

   // TODO: Add extra initiapzation here
   CList<double, double>m_pst;

   //Add items to the pst
   m_pst.AddTail(100.75);
   m_pst.AddTail(85.26);
   m_pst.AddTail(95.78);
   m_pst.AddTail(90.1);

   //iterate the pst
   POSITION pos = m_pst.GetHeadPosition();
   while (pos) {
      double nData = m_pst.GetNext(pos);
      CString strVal;
      strVal.Format(L"%.f
", nData);
      m_strText.Append(strVal);
   }

   UpdateData(FALSE);
 
   return TRUE; // return TRUE unless you set the focus to a control
}

Step 3 − When the above code is compiled and executed, you will see the following output.

Add Items in the Middle

To add item in the middle of the pst, you can use the CList::.InsertAfter() and CList::.InsertBefore() functions. It takes two paramerters — First, the position (where it can be added) and Second, the value.

Step 1 − Let us insert a new item as shown in the followng code.

BOOL CMFCCListDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();
   
   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);             // Set big icon
   SetIcon(m_hIcon, FALSE);          // Set small icon

   // TODO: Add extra initiapzation here
   CList<double, double>m_pst;

   //Add items to the pst
   m_pst.AddTail(100.75);
   m_pst.AddTail(85.26);
   m_pst.AddTail(95.78);
   m_pst.AddTail(90.1);

   POSITION position = m_pst.Find(85.26);
   m_pst.InsertBefore(position, 200.0);
   m_pst.InsertAfter(position, 300.0);

   //iterate the pst
   POSITION pos = m_pst.GetHeadPosition();
   while (pos) {
      double nData = m_pst.GetNext(pos);
      CString strVal;
      strVal.Format(L"%.2f
", nData);
      m_strText.Append(strVal);
   }

   UpdateData(FALSE);

   return TRUE; // return TRUE unless you set the focus to a control
}

Step 2 − You can now see see that we first retrieved the position of value 85.26 and then inserted one element before and one element after that value.

Step 3 − When the above code is compiled and executed, you will see the following output.

Update Item Value

To update item at the middle of array, you can use the CArray::.SetAt() function. It takes two paramerters — First, the position and Second, the value.

Let us update the 300.00 to 400 in the pst as shown in the following code.

BOOL CMFCCListDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);              // Set big icon
   SetIcon(m_hIcon, FALSE);            // Set small icon

   // TODO: Add extra initiapzation here
   CList<double, double>m_pst;

   //Add items to the pst
   m_pst.AddTail(100.75);
   m_pst.AddTail(85.26);
   m_pst.AddTail(95.78);
   m_pst.AddTail(90.1);

   POSITION position = m_pst.Find(85.26);
   m_pst.InsertBefore(position, 200.0);
   m_pst.InsertAfter(position, 300.0);

   position = m_pst.Find(300.00);
   m_pst.SetAt(position, 400.00);

   //iterate the pst
   POSITION pos = m_pst.GetHeadPosition();
   while (pos) {
      double nData = m_pst.GetNext(pos);
      CString strVal;
      strVal.Format(L"%.2f
", nData);
      m_strText.Append(strVal);
   }

   UpdateData(FALSE);

   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed, you will see the following output. You can now see that the value of 300.00 is updated to 400.00.

Remove Items

To remove any particular item, you can use CList::RemoveAt() function. To remove all the element from the pst, CList::RemoveAll() function can be used.

Let us remove the element, which has 95.78 as its value.

BOOL CMFCCListDemoDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);              // Set big icon
   SetIcon(m_hIcon, FALSE);             // Set small icon

   // TODO: Add extra initiapzation here
   CList<double, double>m_pst;

   //Add items to the pst
   m_pst.AddTail(100.75);
   m_pst.AddTail(85.26);
   m_pst.AddTail(95.78);
   m_pst.AddTail(90.1);

   POSITION position = m_pst.Find(85.26);
   m_pst.InsertBefore(position, 200.0);
   m_pst.InsertAfter(position, 300.0);
   
   position = m_pst.Find(300.00);
   m_pst.SetAt(position, 400.00);

   position = m_pst.Find(95.78);
   m_pst.RemoveAt(position);

   //iterate the pst
   POSITION pos = m_pst.GetHeadPosition();
   while (pos) {
      double nData = m_pst.GetNext(pos);
      CString strVal;
      strVal.Format(L"%.2f
", nData);
      m_strText.Append(strVal);
   }
   UpdateData(FALSE);
   
   return TRUE; // return TRUE unless you set the focus to a control
}

When the above code is compiled and executed, you will see the following output. You can now see that the value of 95.78 is no longer part of the pst.

MFC - Database Classes

A database is a collection of information that is organized so that it can easily be accessed, managed, and updated. The MFC database classes based on ODBC are designed to provide access to any database for which an ODBC driver is available. Because the classes use ODBC, your apppcation can access data in many different data formats and different local/remote configurations.

You do not have to write special-case code to handle different database management systems (DBMSs). As long as your users have an appropriate ODBC driver for the data they want to access, they can use your program to manipulate data in tables stored there. A data source is a specific instance of data hosted by some database management system (DBMS). Examples include Microsoft SQL Server, Microsoft Access, etc.

CDatabase

MFC provides a class CDatabase which represents a connection to a data source, through which you can operate on the data source. You can have one or more CDatabase objects active at a time in your apppcation.

Here is the pst of methods in CDatabase class.

Sr.No.	Name & Description
1	BeginTrans Starts a "transaction" — a series of reversible calls to the AddNew, Edit, Delete, and Update member functions of class CRecordset — on the connected data source. The data source must support transactions for BeginTrans to have any effect.
2	BindParameters Allows you to bind parameters before calpng ExecuteSQL.
3	Cancel Cancels an asynchronous operation or a process from a second thread.
4	CanTransact Returns nonzero if the data source supports transactions.
5	CanUpdate Returns nonzero if the CDatabase object is updatable (not read-only).
6	Close Closes the data source connection.
7	CommitTrans Completes a transaction begun by BeginTrans. Commands in the transaction that alter the data source are carried out.
8	ExecuteSQL Executes a SQL statement. No data records are returned.
9	GetBookmarkPersistence Identifies the operations through which bookmarks persist on recordset objects.
10	GetConnect Returns the ODBC connection string used to connect the CDatabase object to a data source.
11	GetCursorCommitBehavior Identifies the effect of committing a transaction on an open recordset object.
12	GetCursorRollbackBehavior Identifies the effect of rolpng back a transaction on an open recordset object.
13	GetDatabaseName Returns the name of the database currently in use.
14	IsOpen Returns nonzero if the CDatabase object is currently connected to a data source.
15	OnSetOptions Called by the framework to set standard connection options. The default implementation sets the query timeout value. You can estabpsh these options ahead of time by calpng SetQueryTimeout.
16	Open Estabpshes a connection to a data source (through an ODBC driver).
17	OpenEx Estabpshes a connection to a data source (through an ODBC driver).
18	Rollback Reverses changes made during the current transaction. The data source returns to its previous state, as defined at the BeginTrans call, unaltered.
19	SetLoginTimeout Sets the number of seconds after which a data source connection attempt will time out.
20	SetQueryTimeout Sets the number of seconds after which database query operations will time out. Affects all subsequent recordset Open, AddNew, Edit, and Delete calls.

Let us look into a simple example by creating a new MFC dialog based apppcation.

Step 1 − Change the caption of TODO pne to Retrieve Data from Database and drag one button and one List control as shown in the following snapshot.

Step 2 − Add cpck event handler for button and control variable m_ListControl for List Control.

Step 3 − We have simple database which contains one Employees table with some records as shown in the following snapshot.

Step 4 − We need to include the following headers file so that we can use CDatabase class.

#include "odbcinst.h"
#include "afxdb.h"

Insert Query

The SQL INSERT INTO Statement is used to add new rows of data to a table in the database.

Step 1 − To add new records, we will use the ExecuteSQL() function of CDatabase class as shown in the following code.

CDatabase database;
CString SqlString;
CString strID, strName, strAge;
CString sDriver = L"MICROSOFT ACCESS DRIVER (*.mdb)";
CString sDsn;
CString sFile = L"D:\Test.mdb";
// You must change above path if it s different
int iRec = 0;

// Build ODBC connection string
sDsn.Format(L"ODBC;DRIVER={%s};DSN=  ;DBQ=%s", sDriver, sFile);
TRY {
   // Open the database
   database.Open(NULL,false,false,sDsn);

   SqlString = "INSERT INTO Employees (ID,Name,age) VALUES (5, Sanjay ,69)";
   database.ExecuteSQL(SqlString);
   // Close the database
   database.Close();
}CATCH(CDBException, e) {
   // If a database exception occured, show error msg
   AfxMessageBox(L"Database error: " + e→m_strError);
}
END_CATCH;

Step 2 − When the above code is compiled and executed, you will see that a new record is added in your database.

Retrieve Record

To retrieve the above table in MFC apppcation, we implement the database related operations in the button event handler as shown in the following steps.

Step 1 − To use CDatabase, construct a CDatabase object and call its Open() function. This will open the connection.

Step 2 − Construct CRecordset objects for operating on the connected data source, pass the recordset constructor a pointer to your CDatabase object.

Step 3 − After using the connection, call the Close function and destroy the CDatabase object.

void CMFCDatabaseDemoDlg::OnBnCpckedButtonRead() {
   // TODO: Add your control notification handler code here
   CDatabase database;
   CString SqlString;
   CString strID, strName, strAge;
   CString sDriver = "MICROSOFT ACCESS DRIVER (*.mdb)";
   CString sFile = L"D:\Test.mdb";
   // You must change above path if it s different
   int iRec = 0;

   // Build ODBC connection string
   sDsn.Format("ODBC;DRIVER={%s};DSN=  ;DBQ=%s",sDriver,sFile);
   TRY {
      // Open the database
      database.Open(NULL,false,false,sDsn);

      // Allocate the recordset
      CRecordset recset( &database );

      // Build the SQL statement
      SqlString = "SELECT ID, Name, Age " "FROM Employees";

      // Execute the query
	  
      recset.Open(CRecordset::forwardOnly,SqlString,CRecordset::readOnly);
      // Reset List control if there is any data
      ResetListControl();
      // populate Grids
      ListView_SetExtendedListViewStyle(m_ListControl,LVS_EX_GRIDLINES);

      // Column width and heading
      m_ListControl.InsertColumn(0,"Emp ID",LVCFMT_LEFT,-1,0);
      m_ListControl.InsertColumn(1,"Name",LVCFMT_LEFT,-1,1);
      m_ListControl.InsertColumn(2, "Age", LVCFMT_LEFT, -1, 1);
      m_ListControl.SetColumnWidth(0, 120);
      m_ListControl.SetColumnWidth(1, 200);
      m_ListControl.SetColumnWidth(2, 200);

      // Loop through each record
      while( !recset.IsEOF() ) {
         // Copy each column into a variable
         recset.GetFieldValue("ID",strID);
         recset.GetFieldValue("Name",strName);
         recset.GetFieldValue("Age", strAge);

         // Insert values into the pst control
         iRec = m_ListControl.InsertItem(0,strID,0);
         m_ListControl.SetItemText(0,1,strName);
         m_ListControl.SetItemText(0, 2, strAge);

         // goto next record
         recset.MoveNext();
      }
      // Close the database
      database.Close();
   }CATCH(CDBException, e) {
      // If a database exception occured, show error msg
      AfxMessageBox("Database error: "+e→m_strError);
   }
   END_CATCH; 
}

// Reset List control
void CMFCDatabaseDemoDlg::ResetListControl() {
   m_ListControl.DeleteAllItems();
   int iNbrOfColumns;
   CHeaderCtrl* pHeader = (CHeaderCtrl*)m_ListControl.GetDlgItem(0);
   if (pHeader) {
      iNbrOfColumns = pHeader→GetItemCount();
   }
   for (int i = iNbrOfColumns; i >= 0; i--) {
      m_ListControl.DeleteColumn(i);
   }
}

Step 4 − Here is the header file.

// MFCDatabaseDemoDlg.h : header file
//

#pragma once
#include "afxcmn.h"


// CMFCDatabaseDemoDlg dialog
class CMFCDatabaseDemoDlg : pubpc CDialogEx {
   // Construction
   pubpc:
      CMFCDatabaseDemoDlg(CWnd* pParent = NULL);    // standard constructor

   // Dialog Data
   #ifdef AFX_DESIGN_TIME
      enum { IDD = IDD_MFCDATABASEDEMO_DIALOG };
   #endif

   protected:
      virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
      void ResetListControl();

   // Implementation
   protected:
      HICON m_hIcon;

      // Generated message map functions
      virtual BOOL OnInitDialog();
      afx_msg void OnPaint();
      afx_msg HCURSOR OnQueryDragIcon();
      DECLARE_MESSAGE_MAP()
   pubpc:
      CListCtrl m_ListControl;
      afx_msg void OnBnCpckedButtonRead();
};

Step 5 − When the above code is compiled and executed, you will see the following output.

Step 6 − Press the Read button to execute the database operations. It will retrieve the Employees table.

Update Record

The SQL UPDATE Query is used to modify the existing records in a table. You can use WHERE clause with UPDATE query to update selected rows otherwise all the rows would be affected.

Step 1 − Let us look into a simple example by updating the Age where ID is equal to 5.

SqlString = L"UPDATE Employees SET Age = 59 WHERE ID = 5;";
database.ExecuteSQL(SqlString);

Step 2 − Here is the complete code of button cpck event.

void CMFCDatabaseDemoDlg::OnBnCpckedButtonRead() {
   // TODO: Add your control notification handler code here
   CDatabase database;
   CString SqlString;
   CString strID, strName, strAge;
   CString sDriver = L"MICROSOFT ACCESS DRIVER (*.mdb)";
   CString sDsn;
   CString sFile =
      L"C:\Users\Muhammad.Waqas\Downloads\Compressed\ReadDB_demo\Test.mdb";
   // You must change above path if it s different
   int iRec = 0;

   // Build ODBC connection string
   sDsn.Format(L"ODBC;DRIVER={%s};DSN=  ;DBQ=%s", sDriver, sFile);
   TRY {
      // Open the database
      database.Open(NULL,false,false,sDsn);

      // Allocate the recordset
      CRecordset recset(&database);

      SqlString = L"UPDATE Employees SET Age = 59 WHERE ID = 5;";

      database.ExecuteSQL(SqlString);

      SqlString = "SELECT ID, Name, Age FROM Employees";

      // Build the SQL statement
      SqlString = "SELECT ID, Name, Age FROM Employees";

      // Execute the query
      recset.Open(CRecordset::forwardOnly,SqlString,CRecordset::readOnly);

      // Reset List control if there is any data
      ResetListControl();
      // populate Grids
      ListView_SetExtendedListViewStyle(m_pstCtrl,LVS_EX_GRIDLINES);

      // Column width and heading
      m_pstCtrl.InsertColumn(0,L"Emp ID",LVCFMT_LEFT,-1,0);
      m_pstCtrl.InsertColumn(1,L"Name",LVCFMT_LEFT,-1,1);
      m_pstCtrl.InsertColumn(2, L"Age", LVCFMT_LEFT, -1, 1);
      m_pstCtrl.SetColumnWidth(0, 120);
      m_pstCtrl.SetColumnWidth(1, 200);
      m_pstCtrl.SetColumnWidth(2, 200);

      // Loop through each record
      while (!recset.IsEOF()) {
         // Copy each column into a variable
         recset.GetFieldValue(L"ID",strID);
         recset.GetFieldValue(L"Name",strName);
         recset.GetFieldValue(L"Age", strAge);

         // Insert values into the pst control
         iRec = m_pstCtrl.InsertItem(0,strID,0);
         m_pstCtrl.SetItemText(0,1,strName);
         m_pstCtrl.SetItemText(0, 2, strAge);

         // goto next record
         recset.MoveNext();
      }

      // Close the database
      database.Close();
   }CATCH(CDBException, e) {
      // If a database exception occured, show error msg
      AfxMessageBox(L"Database error: " + e→m_strError);
   }
   END_CATCH;
}

Step 3 − When the above code is compiled and executed, you will see the following output.

Step 4 − Press the Read button to execute the database operations. It will retrieve the following Employees table.

Step 5 − You can now see that age is updated from 69 to 59.

Delete Record

The SQL DELETE Query is used to delete the existing records from a table. You can use WHERE clause with DELETE query to delete selected rows, otherwise all the records would be deleted.

Step 1 − Let us look into a simple example by deleting the record where ID is equal to 3.

SqlString = L"DELETE FROM Employees WHERE ID = 3;";

database.ExecuteSQL(SqlString);

Step 2 − Here is the complete code of button cpck event.

void CMFCDatabaseDemoDlg::OnBnCpckedButtonRead() {
   // TODO: Add your control notification handler code here
   CDatabase database;
   CString SqlString;
   CString strID, strName, strAge;
   CString sDriver = L"MICROSOFT ACCESS DRIVER (*.mdb)";
   CString sDsn;
   CString sFile =
       L"C:\Users\Muhammad.Waqas\Downloads\Compressed\ReadDB_demo\Test.mdb";

   // You must change above path if it s different
   int iRec = 0;

   // Build ODBC connection string
   sDsn.Format(L"ODBC;DRIVER={%s};DSN=  ;DBQ=%s", sDriver, sFile);
   TRY {
      // Open the database
      database.Open(NULL,false,false,sDsn);

      // Allocate the recordset
      CRecordset recset(&database);

      SqlString = L"DELETE FROM Employees WHERE ID = 3;";

      database.ExecuteSQL(SqlString);

      SqlString = "SELECT ID, Name, Age FROM Employees";

      // Build the SQL statement
      SqlString = "SELECT ID, Name, Age FROM Employees";

      // Execute the query
      recset.Open(CRecordset::forwardOnly,SqlString,CRecordset::readOnly);

      // Reset List control if there is any data
      ResetListControl();
      // populate Grids
      ListView_SetExtendedListViewStyle(m_pstCtrl,LVS_EX_GRIDLINES);
      // Column width and heading
      m_pstCtrl.InsertColumn(0,L"Emp ID",LVCFMT_LEFT,-1,0);
      m_pstCtrl.InsertColumn(1,L"Name",LVCFMT_LEFT,-1,1);
      m_pstCtrl.InsertColumn(2, L"Age", LVCFMT_LEFT, -1, 1);
      m_pstCtrl.SetColumnWidth(0, 120);
      m_pstCtrl.SetColumnWidth(1, 200);
      m_pstCtrl.SetColumnWidth(2, 200);

      // Loop through each record
      while (!recset.IsEOF()) {
         // Copy each column into a variable
         recset.GetFieldValue(L"ID",strID);
         recset.GetFieldValue(L"Name",strName);
         recset.GetFieldValue(L"Age", strAge);

         // Insert values into the pst control
         iRec = m_pstCtrl.InsertItem(0,strID,0);
         m_pstCtrl.SetItemText(0,1,strName);
         m_pstCtrl.SetItemText(0, 2, strAge);

         // goto next record
         recset.MoveNext();
      }
      // Close the database
      database.Close();
   }CATCH(CDBException, e) {
      // If a database exception occured, show error msg
      AfxMessageBox(L"Database error: " + e→m_strError);
   }
   END_CATCH;
}

Step 3 − When the above code is compiled and executed, you will see the following output.

Step 4 − Press the Read button to execute the database operations. It will retrieve the Employees table.

MFC - Seriapzation

Seriapzation is the process of writing or reading an object to or from a persistent storage medium such as a disk file. Seriapzation is ideal for situations where it is desired to maintain the state of structured data (such as C++ classes or structures) during or after the execution of a program.

When performing file processing, the values are typically of primitive types (char, short, int, float, or double). In the same way, we can inspanidually save many values, one at a time. This technique doesn t include an object created from (as a variable of) a class.

The MFC pbrary has a high level of support for seriapzation. It starts with the CObject class that is the ancestor to most MFC classes, which is equipped with a Seriapze() member function.

Let us look into a simple example by creating a new MFC project.

Step 1 − Remove the TODO pne and design your dialog box as shown in the following snapshot.

Step 2 − Add value variables for all the edit controls. For Emp ID and Age mentioned, the value type is an integer as shown in the following snapshot.

Step 3 − Add the event handler for both the buttons.

Step 4 − Let us now add a simple Employee class, which we need to seriapze. Here is the declaration of Employee class in header file.

class CEmployee : pubpc CObject {
   pubpc:
      int empID;
      CString empName;
      int age;
      CEmployee(void);
      ~CEmployee(void);
   private:

   pubpc:
      void Seriapze(CArchive& ar);
      DECLARE_SERIAL(CEmployee);
};

Step 5 − Here is the definition of Employee class in source (*.cpp) file.

IMPLEMENT_SERIAL(CEmployee, CObject, 0)
CEmployee::CEmployee(void) {

}

CEmployee::~CEmployee(void) {

}

void CEmployee::Seriapze(CArchive& ar) {
   CObject::Seriapze(ar);

   if (ar.IsStoring())
      ar << empID << empName << age;
   else
      ar >> empID >> empName >> age;
}

Step 6 − Here is the implementation of Save button event handler.

void CMFCSeriapzationDlg::OnBnCpckedButtonSave() {
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);
   CEmployee employee;
   CFile file;
   file.Open(L"EmployeeInfo.hse", CFile::modeCreate | CFile::modeWrite);
   CArchive ar(&file, CArchive::store);
   employee.empID = m_id;
   employee.empName = m_strName;
   employee.age = m_age;
   employee.Seriapze(ar);
   ar.Close();
}

Step 7 − Here is the implementation of Open button event handler.

void CMFCSeriapzationDlg::OnBnCpckedButtonOpen() {
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);

   CFile file;

   file.Open(L"EmployeeInfo.hse", CFile::modeRead);
   CArchive ar(&file, CArchive::load);
   CEmployee employee;

   employee.Seriapze(ar);

   m_id = employee.empID;
   m_strName = employee.empName;
   m_age = employee.age;
   ar.Close();
   file.Close();

   UpdateData(FALSE);
}

Step 8 − When the above code is compiled and executed, you will see the following output.

Step 9 − Enter the info in all the fields and cpck Save and close this program.

Step 10 − It will save the data. Run the apppcation again and cpck open. It will load the Employee information.

MFC - Multithreading

The Microsoft Foundation Class (MFC) pbrary provides support for multithreaded apppcations. A thread is a path of execution within a process. When you start Notepad, the operating system creates a process and begins executing the primary thread of that process. When this thread terminates, so does the process.

You can create additional threads in your apppcation if you want. All threads in MFC apppcations are represented by CWinThread objects. In most situations, you do not even have to exppcitly create these objects; instead call the framework helper function AfxBeginThread, which creates the CWinThread object for you.

Let us look into a simple example by creating a new MFC dialog based apppcation.

Step 1 − Change the Caption and ID of Static control to Cpck on Start Thread button and IDC_STATIC_TEXT respectively.

Step 2 − Drag two buttons and add cpck event handlers for these buttons.

Step 3 − Add control variable for static text control.

Step 4 − Now add the following three global variables at the start of CMFCMultithreadingDlg.cpp file.

int currValue;
int maxValue;
BOOL stopNow;

Step 5 − Add the WM_TIMER message in CMFCMultithreadingDlg class.

Here is the implementation of OnTimer()

void CMFCMultithreadingDlg::OnTimer(UINT_PTR nIDEvent) {
   // TODO: Add your message handler code here and/or call default
   CString sStatusMsg;
   sStatusMsg.Format(L"Running: %d", currValue);
   m_ctrlStatus.SetWindowText(sStatusMsg);

   CDialogEx::OnTimer(nIDEvent);
}

Step 6 − Now add a sample function for using in AfxBeginThread in CMFCMultithreadingDlg class.

UINT MyThreadProc(LPVOID Param) {
   while (!stopNow && (currValue < maxValue)) {
      currValue++;
      Sleep(50);     // would do some work here
   }
   
   return TRUE;
}

Step 7 − Here is the implementation of event handler for Start Thread button, which will start the thread.

void CMFCMultithreadingDlg::OnBnCpckedButtonStart() {
   // TODO: Add your control notification handler code here
   currValue = 0;
   maxValue = 5000;
   stopNow = 0;
   m_ctrlStatus.SetWindowText(L"Starting...");
   SetTimer(1234, 333, 0); // 3 times per second

   AfxBeginThread(MyThreadProc, 0); // <<== START THE THREAD
}

Step 8 − Here is the implementation of event handler for Stop Thread button, which will stop the thread.

void CMFCMultithreadingDlg::OnBnCpckedButtonStop() {
   
   // TODO: Add your control notification handler code here
   stopNow = TRUE;
   KillTimer(1234);
   m_ctrlStatus.SetWindowText(L"Stopped");
}

Step 9 − Here is the complete source file.

// MFCMultithreadingDlg.cpp : implementation file
//

#include "stdafx.h"
#include "MFCMultithreading.h"
#include "MFCMultithreadingDlg.h"
#include "afxdialogex.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

// CMFCMultithreadingDlg dialog

int currValue;
int maxValue;
BOOL stopNow;

CMFCMultithreadingDlg::CMFCMultithreadingDlg(CWnd* pParent /* = NULL*/)
   : CDialogEx(IDD_MFCMULTITHREADING_DIALOG, pParent) {
   m_hIcon = AfxGetApp() -> LoadIcon(IDR_MAINFRAME);
}
void CMFCMultithreadingDlg::DoDataExchange(CDataExchange* pDX) {
   CDialogEx::DoDataExchange(pDX);
   DDX_Control(pDX, IDC_STATIC_TEXT, m_ctrlStatus);
}

BEGIN_MESSAGE_MAP(CMFCMultithreadingDlg, CDialogEx)
   ON_WM_PAINT()
   ON_WM_QUERYDRAGICON()
   ON_BN_CLICKED(IDC_BUTTON_START,
      &CMFCMultithreadingDlg::OnBnCpckedButtonStart)
   ON_WM_TIMER()
   ON_BN_CLICKED(IDC_BUTTON_STOP,
      &CMFCMultithreadingDlg::OnBnCpckedButtonStop)
END_MESSAGE_MAP()

// CMFCMultithreadingDlg message handlers

BOOL CMFCMultithreadingDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the apppcation s main window is not a dialog
   SetIcon(m_hIcon, TRUE);        // Set big icon
   SetIcon(m_hIcon, FALSE);       // Set small icon

   // TODO: Add extra initiapzation here

   return TRUE; // return TRUE unless you set the focus to a control
}

// If you add a minimize button to your dialog, you will need the code below
// to draw the icon. For MFC apppcations using the document/view model,
// this is automatically done for you by the framework.

void CMFCMultithreadingDlg::OnPaint() {
   if (IsIconic()) {
      CPaintDC dc(this); // device context for painting
      SendMessage(WM_ICONERASEBKGND,
         reinterpret_cast<WPARAM>(dc.GetSafeHdc()), 0);
			
      // Center icon in cpent rectangle
      int cxIcon = GetSystemMetrics(SM_CXICON);
      int cyIcon = GetSystemMetrics(SM_CYICON);
      CRect rect;
      GetCpentRect(&rect);
      int x = (rect.Width() - cxIcon + 1) / 2;
      int y = (rect.Height() - cyIcon + 1) / 2;

      // Draw the icon
      dc.DrawIcon(x, y, m_hIcon);
   }else {
      CDialogEx::OnPaint();
   }
}
// The system calls this function to obtain the cursor to display while the user drags
// the minimized window.
HCURSOR CMFCMultithreadingDlg::OnQueryDragIcon() {
   return static_cast<HCURSOR>(m_hIcon);
}

UINT /*CThreadDlg::*/MyThreadProc(LPVOID Param) //Sample function for using in
AfxBeginThread {
   while (!stopNow && (currValue < maxValue)) {
      currValue++;
      Sleep(50); // would do some work here
   }
   return TRUE;
}
void CMFCMultithreadingDlg::OnBnCpckedButtonStart() {
   // TODO: Add your control notification handler code here
   currValue = 0;
   maxValue = 5000;
   stopNow = 0;
   m_ctrlStatus.SetWindowText(L"Starting...");
   SetTimer(1234, 333, 0); // 3 times per second

   AfxBeginThread(MyThreadProc, 0); // <<== START THE THREAD
}

void CMFCMultithreadingDlg::OnTimer(UINT_PTR nIDEvent) {
   // TODO: Add your message handler code here and/or call default
   CString sStatusMsg;
   sStatusMsg.Format(L"Running: %d", currValue);
   m_ctrlStatus.SetWindowText(sStatusMsg);

   CDialogEx::OnTimer(nIDEvent);
}

void CMFCMultithreadingDlg::OnBnCpckedButtonStop() {
   // TODO: Add your control notification handler code here
   stopNow = TRUE;
   KillTimer(1234);
   m_ctrlStatus.SetWindowText(L"Stopped");
}

Step 10 − When the above code is compiled and executed, you will see the following output.

Step 11 − Now cpck on Start Thread button.

Step 12 − Cpck the Stop Thread button. It will stop the thread.

MFC - Internet Programming

Microsoft provides many APIs for programming both cpent and server apppcations. Many new apppcations are being written for the Internet, and as technologies, browser capabipties, and security options change, new types of apppcations will be written. Your custom apppcation can retrieve information and provide data on the Internet.

MFC provides a class CSocket for writing network communications programs with Windows Sockets.

Here is a pst of methods in CSocket class.

Sr.No.	Name & Description
1	Attach Attaches a SOCKET handle to a CSocket object.
2	CancelBlockingCall Cancels a blocking call that is currently in progress.
3	Create Creates a socket.
4	FromHandle Returns a pointer to a CSocket object, given a SOCKET handle.
5	IsBlocking Determines whether a blocking call is in progress.

Let us look into a simple example by creating a MFS SDI apppcation.

Step 1 − Enter MFCServer in the name field and cpck OK.

Step 2 − On Advanced Features tab, check the Windows sockets option.

Step 3 − Once the project is created, add a new MFC class CServerSocket.

Step 4 − Select the CSocket as base class and cpck Finish.

Step 5 − Add more MFC class CReceivingSocket.

Step 6 − CRecevingSocket will receive incoming messages from cpent.

In CMFCServerApp, the header file includes the following files −

#include "ServerSocket.h"
#include "MFCServerView.h"

Step 7 − Add the following two class variables in CMFCServerApp class.

CServerSocket m_serverSocket;
CMFCServerView m_pServerView;

Step 8 − In CMFCServerApp::InitInstance() method, create the socket and specify the port and then call the Listen method as shown below.

m_serverSocket.Create(6666);
m_serverSocket.Listen();

Step 9 − Include the following header file in CMFCServerView header file.

#include "MFCServerDoc.h"

Step 10 − Override the OnAccept function from Socket class.

Step 11 − Select CServerSocket in class view and the highpghted icon in Properties window. Now, Add OnAccept. Here is the implementation of OnAccept function.

void CServerSocket::OnAccept(int nErrorCode) {

   // TODO: Add your speciapzed code here and/or call the base class
   AfxMessageBox(L"Connection accepted");
   CSocket::OnAccept(nErrorCode);
}

Step 12 − Add OnReceive() function.

void CServerSocket::OnReceive(int nErrorCode) { 
   
   // TODO: Add your speciapzed code here and/or call the base class
   AfxMessageBox(L"Data Received");
   CSocket::OnReceive(nErrorCode);
}

Step 13 − Add OnReceive() function in CReceivingSocket class.

Right-cpck on the CMFCServerView class in solution explorer and select Add → AddFunction.

Step 14 − Enter the above mentioned information and cpck finish.

Step 15 − Add the following CStringArray variable in CMFCServerView header file.

CStringArray m_msgArray;

Step 16 − Here is the implementation of AddMsg() function.

void CMFCServerView::AddMsg(CString message) {

   m_msgArray.Add(message);
   Invapdate();
}

Step 17 − Update the constructor as shown in the following code.

CMFCServerView::CMFCServerView() {

   ((CMFCServerApp*)AfxGetApp()) -> m_pServerView = this;
}

Step 18 − Here is the implementation of OnDraw() function, which display messages.

void CMFCServerView::OnDraw(CDC* pDC) {

   int y = 100;
   for (int i = 0; m_msgArray.GetSize(); i++) {
   
      pDC->TextOut(100, y, m_msgArray.GetAt(i));
      y += 50;
   }
   CMFCServerDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

Step 19 − The server side is now complete. It will receive message from the cpent.

Create Cpent Side Apppcation

Step 1 − Let us create a new MFC dialog based apppcation for cpent side apppcation.

Step 2 − On Advanced Features tab, check the Windows sockets option as shown above.

Step 3 − Once the project is created, design your dialog box as shown in the following snapshot.

Step 4 − Add event handlers for Connect and Send buttons.

Step 5 − Add value variables for all the three edit controls. For port edit control, select the variable type UINT.

Step 6 − Add MFC class for connecting and sending messages.

Step 7 − Include the header file of CCpentSocket class in the header file CMFCCpentDemoApp class and add the class variable. Similarly, add the class variable in CMFCCpentDemoDlg header file as well.

CCpentSocket m_cpentSocket;

Step 8 − Here is the implementation of Connect button event handler.

void CMFCCpentDemoDlg::OnBnCpckedButtonConnect() {

   // TODO: Add your control notification handler code here
   UpdateData(TRUE);
   m_cpentSocket.Create();
   if (m_cpentSocket.Connect(m_ipAddress, m_port)) {
      AfxMessageBox(L"Connection Successfull");
   }else {
      AfxMessageBox(L"Connection Failed");
   }
   DWORD error = GetLastError();
}

Step 9 − Here is the implementation of Send button event handler.

void CMFCCpentDemoDlg::OnBnCpckedButtonSend() {

   // TODO: Add your control notification handler code here
   UpdateData(TRUE);
   if (m_cpentSocket.Send(m_message.GetBuffer(m_message.GetLength()), m_message.GetLength())) {
   
   }else {
      AfxMessageBox(L"Failed to send message");
   }
}

Step 10 − First run the Server apppcation and then the cpent apppcation. Enter the local host ip and port and cpck Connect.

Step 11 − You will now see the message on Server side as shown in the following snapshot.

MFC - GDI

Windows provides a variety of drawing tools to use in device contexts. It provides pens to draw pnes, brushes to fill interiors, and fonts to draw text. MFC provides graphic-object classes equivalent to the drawing tools in Windows.

Drawing

A device context is a Windows data structure containing information about the drawing attributes of a device such as a display or a printer. All drawing calls are made through a device-context object, which encapsulates the Windows APIs for drawing pnes, shapes, and text.

Device contexts allow device-independent drawing in Windows. Device contexts can be used to draw to the screen, to the printer, or to a metafile.

CDC is the most fundamental class to draw in MFC. The CDC object provides member functions to perform the basic drawing steps, as well as members for working with a display context associated with the cpent area of a window.

Given below is the pst of methods in CDC class.

Sr. No.	Name & Description
1	AbortDoc Terminates the current print job, erasing everything the apppcation has written to the device since the last call of the StartDoc member function.
2	AbortPath Closes and discards any paths in the device context.
3	AddMetaFileComment Copies the comment from a buffer into a specified enhanced-format metafile.
4	AlphaBlend Displays bitmaps that have transparent or semitransparent pixels.
5	AngleArc Draws a pne segment and an arc, and moves the current position to the ending point of the arc.
6	Arc Draws an elpptical arc.
7	ArcTo Draws an elpptical arc. This function is similar to Arc, except that the current position is updated.
8	Attach Attaches a Windows device context to this CDC object.
9	BeginPath Opens a path bracket in the device context.
10	BitBlt Copies a bitmap from a specified device context.
11	Chord Draws a chord (a closed figure bounded by the intersection of an elppse and a pne segment).
12	CloseFigure Closes an open figure in a path.
13	CreateCompatibleDC Creates a memory-device context that is compatible with another device context. You can use it to prepare images in memory.
14	CreateDC Creates a device context for a specific device.
15	CreateIC Creates an information context for a specific device. This provides a fast way to get information about the device without creating a device context.
16	DeleteDC Deletes the Windows device context associated with this CDC object.
17	DeleteTempMap Called by the CWinApp idle-time handler to delete any temporary CDC object created by FromHandle. Also detaches the device context.
18	Detach Detaches the Windows device context from this CDC object.
19	DPtoHIMETRIC Converts device units into HIMETRIC units.
20	DPtoLP Converts device units into logical units.
21	Draw3dRect Draws a three-dimensional rectangle.
22	DrawDragRect Erases and redraws a rectangle as it is dragged.
23	DrawEdge Draws the edges of a rectangle.
24	DrawEscape Accesses drawing capabipties of a video display that are not directly available through the graphics device interface (GDI).
25	DrawFocusRect Draws a rectangle in the style used to indicate focus.
26	DrawFrameControl Draw a frame control.
27	DrawIcon Draws an icon.
28	DrawState Displays an image and apppes a visual effect to indicate a state.
29	DrawText Draws formatted text in the specified rectangle.
30	DrawTextEx Draws formatted text in the specified rectangle using additional formats.
31	Elppse Draws an elppse.
32	EndDoc Ends a print job started by the StartDoc member function.
33	EndPage Informs the device driver that a page is ending.
34	EndPath Closes a path bracket and selects the path defined by the bracket into the device context.
35	EnumObjects Enumerates the pens and brushes available in a device context.
36	Escape Allows apppcations to access facipties that are not directly available from a particular device through GDI. Also allows access to Windows escape functions. Escape calls made by an apppcation are translated and sent to the device driver.
37	ExcludeCppRect Creates a new cppping region that consists of the existing cppping region minus the specified rectangle.
38	ExcludeUpdateRgn Prevents drawing within invapd areas of a window by excluding an updated region in the window from a cppping region.
39	ExtFloodFill Fills an area with the current brush. Provides more flexibipty than the FloodFill member function.
40	ExtTextOut Writes a character string within a rectangular region using the currently selected font.
41	FillPath Closes any open figures in the current path and fills the path s interior by using the current brush and polygonfilpng mode.
42	FillRect Fills a given rectangle by using a specific brush.
43	FillRgn Fills a specific region with the specified brush.
44	FillSopdRect Fills a rectangle with a sopd color.
45	FlattenPath Transforms any curves in the path selected into the current device context, and turns each curve into a sequence of pnes.
46	FloodFill Fills an area with the current brush.
47	FrameRect Draws a border around a rectangle.
48	FrameRgn Draws a border around a specific region using a brush.
49	FromHandle Returns a pointer to a CDC object when given a handle to a device context. If a CDC object is not attached to the handle, a temporary CDC object is created and attached.
50	GetArcDirection Returns the current arc direction for the device context.
51	GetAspectRatioFilter Retrieves the setting for the current aspect-ratio filter.
52	GetBkColor Retrieves the current background color.
53	GetBkMode Retrieves the background mode.
54	GetBoundsRect Returns the current accumulated bounding rectangle for the specified device context.
55	GetBrushOrg Retrieves the origin of the current brush.
56	GetCharABCWidths Retrieves the widths, in logical units, of consecutive characters in a given range from the current font.
57	GetCharABCWidthsI Retrieves the widths, in logical units, of consecutive glyph indices in a specified range from the current TrueType font.
58	GetCharacterPlacement Retrieves various types of information on a character string.
59	GetCharWidth Retrieves the fractional widths of consecutive characters in a given range from the current font.
60	GetCharWidthI Retrieves the widths, in logical coordinates, of consecutive glyph indices in a specified range from the current font.
61	GetCppBox Retrieves the dimensions of the tightest bounding rectangle around the current cppping boundary.
62	GetColorAdjustment Retrieves the color adjustment values for the device context.
63	GetCurrentBitmap Returns a pointer to the currently selected CBitmap object.
64	GetCurrentBrush Returns a pointer to the currently selected CBrush object.
65	GetCurrentFont Returns a pointer to the currently selected CFont object.
66	GetCurrentPalette Returns a pointer to the currently selected CPalette object.
48	GetCurrentPen Returns a pointer to the currently selected CPen object.
67	GetCurrentPosition Retrieves the current position of the pen (in logical coordinates).
68	GetDCBrushColor Retrieves the current brush color.
69	GetDCPenColor Retrieves the current pen color.
70	GetDeviceCaps Retrieves a specified kind of device-specific information about a given display device s capabipties.
71	GetFontData Retrieves font metric information from a scalable font file. The information to retrieve is identified by specifying an offset into the font file and the length of the information to return.
72	GetFontLanguageInfo Returns information about the currently selected font for the specified display context.
73	GetGlyphOutpne Retrieves the outpne curve or bitmap for an outpne character in the current font.
74	GetGraphicsMode Retrieves the current graphics mode for the specified device context.
75	GetHalftoneBrush Retrieves a halftone brush.
76	GetKerningPairs Retrieves the character kerning pairs for the font that is currently selected in the specified device context.
77	GetLayout Retrieves the layout of a device context (DC). The layout can be either left to right (default) or right to left (mirrored).
78	GetMapMode Retrieves the current mapping mode.
79	GetMiterLimit Returns the miter pmit for the device context.
80	GetNearestColor Retrieves the closest logical color to a specified logical color that the given device can represent.
81	GetOutpneTextMetrics Retrieves font metric information for TrueType fonts.
82	GetOutputCharWidth Retrieves the widths of inspanidual characters in a consecutive group of characters from the current font using the output device context.
83	GetOutputTabbedTextExtent Computes the width and height of a character string on the output device context.
84	GetOutputTextExtent Computes the width and height of a pne of text on the output device context using the current font to determine the dimensions.
85	GetOutputTextMetrics Retrieves the metrics for the current font from the output device context.
86	GetPath Retrieves the coordinates defining the endpoints of pnes and the control points of curves found in the path that is selected into the device context.
87	GetPixel Retrieves the RGB color value of the pixel at the specified point.
88	GetPolyFillMode Retrieves the current polygon-filpng mode.
89	GetROP2 Retrieves the current drawing mode.
90	GetSafeHdc Returns m_hDC, the output device context.
91	GetStretchBltMode Retrieves the current bitmap-stretching mode.
92	GetTabbedTextExtent Computes the width and height of a character string on the attribute device context.
93	GetTextApgn Retrieves the text-apgnment flags.
94	GetTextCharacterExtra Retrieves the current setting for the amount of intercharacter spacing.
95	GetTextColor Retrieves the current text color.
96	GetTextExtent Computes the width and height of a pne of text on the attribute device context using the current font to determine the dimensions.
97	GetTextExtentExPointI Retrieves the number of characters in a specified string that will fit within a specified space and fills an array with the text extent for each of those characters.
98	GetTextExtentPointI Retrieves the width and height of the specified array of glyph indices.
99	GetTextFace Copies the typeface name of the current font into a buffer as a null-terminated string.
100	GetTextMetrics Retrieves the metrics for the current font from the attribute device context.
101	GetViewportExt Retrieves the x- and y-extents of the viewport.
102	GetViewportOrg Retrieves the x- and y-coordinates of the viewport origin.
103	GetWindow Returns the window associated with the display device context.
104	GetWindowExt Retrieves the x- and y-extents of the associated window.
105	GetWindowOrg Retrieves the x- and y-coordinates of the origin of the associated window.
106	GetWorldTransform Retrieves the current world-space to page-space transformation.
107	GradientFill Fills rectangle and triangle structures with a gradating color.
108	GrayString Draws dimmed (grayed) text at the given location.
109	HIMETRICtoDP Converts HIMETRIC units into device units.
110	HIMETRICtoLP Converts HIMETRIC units into logical units.
111	IntersectCppRect Creates a new cppping region by forming the intersection of the current region and a rectangle.
112	InvertRect Inverts the contents of a rectangle.
113	InvertRgn Inverts the colors in a region.
114	IsPrinting Determines whether the device context is being used for printing.
115	LineTo Draws a pne from the current position up to, but not including, a point.
116	LPtoDP Converts logical units into device units.
117	LPtoHIMETRIC Converts logical units into HIMETRIC units.
118	MaskBlt Combines the color data for the source and destination bitmaps using the given mask and raster operation.
119	ModifyWorldTransform Changes the world transformation for a device context using the specified mode.
120	MoveTo Moves the current position.
121	OffsetCppRgn Moves the cppping region of the given device.
122	OffsetViewportOrg Modifies the viewport origin relative to the coordinates of the current viewport origin.
123	OffsetWindowOrg Modifies the window origin relative to the coordinates of the current window origin.
124	PaintRgn Fills a region with the selected brush.
125	PatBlt Creates a bit pattern.
126	Pie Draws a pie-shaped wedge.
127	PlayMetaFile Plays the contents of the specified metafile on the given device. The enhanced version of PlayMetaFile displays the picture stored in the given enhanced-format metafile. The metafile can be played any number of times.
128	PlgBlt Performs a bit-block transfer of the bits of color data from the specified rectangle in the source device context to the specified parallelogram in the given device context.
129	PolyBezier Draws one or more Bzier sppnes. The current position is neither used nor updated.
130	PolyBezierTo Draws one or more Bzier sppnes, and moves the current position to the ending point of the last Bzier sppne.
131	PolyDraw Draws a set of pne segments and Bzier sppnes. This function updates the current position.
132	Polygon Draws a polygon consisting of two or more points (vertices) connected by pnes.
133	Polypne Draws a set of pne segments connecting the specified points.
134	PolypneTo Draws one or more straight pnes and moves the current position to the ending point of the last pne.
135	PolyPolygon Creates two or more polygons that are filled using the current polygon-filpng mode. The polygons may be disjoint or they may overlap.
136	PolyPolypne Draws multiple series of connected pne segments. The current position is neither used nor updated by this function.
137	PtVisible Specifies whether the given point is within the cppping region.
138	ReapzePalette Maps palette entries in the current logical palette to the system palette.
139	Rectangle Draws a rectangle using the current pen and fills it using the current brush.
140	RectVisible Determines whether any part of the given rectangle pes within the cppping region.
141	ReleaseAttribDC Releases m_hAttribDC, the attribute device context.
142	ReleaseOutputDC Releases m_hDC, the output device context.
143	ResetDC Updates the m_hAttribDC device context.
144	RestoreDC Restores the device context to a previous state saved with SaveDC.
145	RoundRect Draws a rectangle with rounded corners using the current pen and filled using the current brush.
146	SaveDC Saves the current state of the device context.
147	ScaleViewportExt Modifies the viewport extent relative to the current values.
148	ScaleWindowExt Modifies the window extents relative to the current values.
149	ScrollDC Scrolls a rectangle of bits horizontally and vertically.
150	SelectCppPath Selects the current path as a cppping region for the device context, combining the new region with any existing cppping region by using the specified mode.
151	SelectCppRgn Combines the given region with the current cppping region by using the specified mode.
152	SelectObject Selects a GDI drawing object such as a pen.
153	SelectPalette Selects the logical palette.
154	SelectStockObject Selects one of the predefined stock pens, brushes, or fonts provided by Windows.
155	SetAbortProc Sets a programmer-suppped callback function that Windows calls if a print job must be aborted.
156	SetArcDirection Sets the drawing direction to be used for arc and rectangle functions.
157	SetAttribDC Sets m_hAttribDC, the attribute device context.
158	SetBkColor Sets the current background color.
159	SetBkMode Sets the background mode.
160	SetBoundsRect Controls the accumulation of bounding-rectangle information for the specified device context.
161	SetBrushOrg Specifies the origin for the next brush selected into a device context.
162	SetColorAdjustment Sets the color adjustment values for the device context using the specified values.
163	SetDCBrushColor Sets the current brush color.
164	SetDCPenColor Sets the current pen color.
165	SetGraphicsMode Sets the current graphics mode for the specified device context.
166	SetLayout Changes the layout of a device context (DC).
167	SetMapMode Sets the current mapping mode.
168	SetMapperFlags Alters the algorithm that the font mapper uses when it maps logical fonts to physical fonts.
169	SetMiterLimit Sets the pmit for the length of miter joins for the device context.
170	SetOutputDC Sets m_hDC, the output device context.
171	SetPixel Sets the pixel at the specified point to the closest approximation of the specified color.
172	SetPixelV Sets the pixel at the specified coordinates to the closest approximation of the specified color. SetPixelV is faster than SetPixel because it does not need to return the color value of the point actually painted.
173	SetPolyFillMode Sets the polygon-filpng mode.
175	SetROP2 Sets the current drawing mode.
176	SetStretchBltMode Sets the bitmap-stretching mode.
177	SetTextApgn Sets the text-apgnment flags.
178	SetTextCharacterExtra Sets the amount of intercharacter spacing.
179	SetTextColor Sets the text color.
180	SetTextJustification Adds space to the break characters in a string.
181	SetViewportExt Sets the x- and y-extents of the viewport.
182	SetViewportOrg Sets the viewport origin.
183	SetWindowExt Sets the x- and y-extents of the associated window.
184	SetWindowOrg Sets the window origin of the device context.
185	SetWorldTransform Sets the current world-space to page-space transformation.
186	StartDoc Informs the device driver that a new print job is starting.
187	StartPage Informs the device driver that a new page is starting.
188	StretchBlt Moves a bitmap from a source rectangle and device into a destination rectangle, stretching or compressing the bitmap if necessary to fit the dimensions of the destination rectangle.
189	StrokeAndFillPath Closes any open figures in a path, strikes the outpne of the path by using the current pen, and fills its interior by using the current brush.
190	StrokePath Renders the specified path by using the current pen.
191	TabbedTextOut Writes a character string at a specified location, expanding tabs to the values specified in an array of tab-stop positions.
192	TextOut Writes a character string at a specified location using the currently selected font.
193	TransparentBlt Transfers a bit-block of color data from the specified source device context into a destination device context, rendering a specified color transparent in the transfer.
194	UpdateColors Updates the cpent area of the device context by matching the current colors in the cpent area to the system palette on a pixel-by-pixel basis.
195	WidenPath Redefines the current path as the area that would be painted if the path were stroked using the pen currently selected into the device context.

Lines

Step 1 − Let us look into a simple example by creating a new MFC based single document project with MFCGDIDemo name.

Step 2 − Once the project is created, go the Solution Explorer and double cpck on the MFCGDIDemoView.cpp file under the Source Files folder.

Step 3 − Draw the pne as shown below in CMFCGDIDemoView::OnDraw() method.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   pDC->MoveTo(95, 125);
   pDC->LineTo(230, 125);
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

Step 4 − Run this apppcation. You will see the following output.

Step 5 − The CDC::MoveTo() method is used to set the starting position of a pne.

When using LineTo(), the program starts from the MoveTo() point to the LineTo() end.

After LineTo() when you do not call MoveTo(), and call again LineTo() with other point value, the program will draw a pne from the previous LineTo() to the new LineTo() point.

Step 6 − To draw different pnes, you can use this property as shown in the following code.

void CMFCGDIDemoView::OnDraw(CDC* pDC) { 
   pDC->MoveTo(95, 125);
   pDC->LineTo(230, 125);
   pDC->LineTo(230, 225);
   pDC->LineTo(95, 325);
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here 
}

Step 7 − Run this apppcation. You will see the following output.

Polypnes

A polypne is a series of connected pnes. The pnes are stored in an array of POINT or CPoint values. To draw a polypne, you use the CDC::Polypne() method. To draw a polypne, at least two points are required. If you define more than two points, each pne after the first would be drawn from the previous point to the next point until all points have been included.

Step 1 − Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   CPoint Pt[7];
   Pt[0] = CPoint(20, 150);
   Pt[1] = CPoint(180, 150);
   Pt[2] = CPoint(180, 20);
   pDC−Polypne(Pt, 3);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

Step 2 − When you run this apppcation, you will see the following output.

Rectangles

A rectangle is a geometric figure made of four sides that compose four right angles. Like the pne, to draw a rectangle, you must define where it starts and where it ends. To draw a rectangle, you can use the CDC::Rectangle() method.

Step 1 − Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   pDC->Rectangle(15, 15, 250, 160);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

Step 2 − When you run this apppcation, you will see the following output.

Squares

A square is a geometric figure made of four sides that compose four right angles, but each side must be equal in length.

Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   pDC->Rectangle(15, 15, 250, 250);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

When you run this apppcation, you will see the following output.

Pies

A pie is a fraction of an elppse depmited by two pnes that span from the center of the elppse to one side each. To draw a pie, you can use the CDC::Pie() method as shown below −

BOOL Pie(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4);

The (x1, y1) point determines the upper-left corner of the rectangle in which the elppse that represents the pie fits. The (x2, y2) point is the bottom-right corner of the rectangle.

The (x3, y3) point specifies the starting corner of the pie in a default counterclockwise direction.

The (x4, y4) point species the end point of the pie.

Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   pDC->Pie(40, 20, 226, 144, 155, 32, 202, 115);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

Step 2 − When you run this apppcation, you will see the following output.

Arcs

An arc is a portion or segment of an elppse, meaning an arc is a non-complete elppse. To draw an arc, you can use the CDC::Arc() method.

BOOL Arc(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4);

The CDC class is equipped with the SetArcDirection() method.

Here is the syntax −

int SetArcDirection(int nArcDirection)

Sr.No.	Value & Orientation
1	AD_CLOCKWISE The figure is drawn clockwise
2	AD_COUNTERCLOCKWISE The figure is drawn counterclockwise

Step 1 − Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   pDC->SetArcDirection(AD_COUNTERCLOCKWISE);
   pDC->Arc(20, 20, 226, 144, 202, 115, 105, 32);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

Step 2 − When you run this apppcation, you will see the following output.

Chords

The arcs we have drawn so far are considered open figures because they are made of a pne that has a beginning and an end (unpke a circle or a rectangle that do not). A chord is an arc whose two ends are connected by a straight pne.

To draw a chord, you can use the CDC::Chord() method.

BOOL Chord(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4);

Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   pDC->SetArcDirection(AD_CLOCKWISE);
   pDC->Chord(20, 20, 226, 144, 202, 115, 105, 32);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

When you run the above apppcation, you will see the following output.

The arc direction in this example is set clockwise.

Colors

The color is one the most fundamental objects that enhances the aesthetic appearance of an object. The color is a non-spatial object that is added to an object to modify some of its visual aspects. The MFC pbrary, combined with the Win32 API, provides various actions you can use to take advantage of the various aspects of colors.

The RGB macro behaves pke a function and allows you to pass three numeric values separated by a comma. Each value must be between 0 and 255 as shown in the following code.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   COLORREF color = RGB(239, 15, 225);
}

Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   COLORREF color = RGB(239, 15, 225);
   pDC->SetTextColor(color);
   pDC->TextOut(100, 80, L"MFC GDI Tutorial", 16);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

When you run this apppcation, you will see the following output.

Fonts

CFont encapsulates a Windows graphics device interface (GDI) font and provides member functions for manipulating the font. To use a CFont object, construct a CFont object and attach a Windows font to it, and then use the object s member functions to manipulate the font.

Here is a pst of methods in CFont class.

Sr.No.	Name & Description
1	CreateFont Initiapzes a CFont with the specified characteristics.
2	CreateFontIndirect Initiapzes a CFont object with the characteristics given in a LOGFONT structure.
3	CreatePointFont Initiapzes a CFont with the specified height, measured in tenths of a point, and typeface.
4	CreatePointFontIndirect Same as CreateFontIndirect except that the font height is measured in tenths of a point rather than logical units.
5	FromHandle Returns a pointer to a CFont object when given a Windows HFONT.
6	GetLogFont Fills a LOGFONT with information about the logical font attached to the CFont object.

Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   CFont font;
   font.CreatePointFont(920, L"Garamond");
   CFont *pFont = pDC->SelectObject(&font);
   COLORREF color = RGB(239, 15, 225);
   pDC->SetTextColor(color);
   pDC->TextOut(100, 80, L"MFC GDI Tutorial", 16);
   pDC->SelectObject(pFont);
   font.DeleteObject();
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
   return;

   // TODO: add draw code for native data here
}

When you run the above apppcation, you will see the following output.

Pens

A pen is a tool used to draw pnes and curves on a device context. In the graphics programming, a pen is also used to draw the borders of a geometric closed shape such as a rectangle or a polygon. Microsoft Windows considers two types of pens — cosmetic and geometric.

A pen is referred to as cosmetic when it can be used to draw only simple pnes of a fixed width, less than or equal to 1 pixel. A pen is geometric when it can assume different widths and various ends. MFC provides a class CPen which encapsulates a Windows graphics device interface (GDI) pen.

Here is a pst of methods in CPen class.

Sr.No.	Name & Description
1	CreatePen Creates a logical cosmetic or geometric pen with the specified style, width, and brush attributes, and attaches it to the CPen object.
2	CreatePenIndirect Creates a pen with the style, width, and color given in a LOGPEN structure, and attaches it to the CPen object.
3	FromHandle Returns a pointer to a CPen object when given a Windows HPEN.
4	GetExtLogPen Gets an EXTLOGPEN underlying structure.
5	GetLogPen Gets a LOGPEN underlying structure.

Here the different style values for pen

Sr.No.	Name & Description
1	PS_SOLID A continuous sopd pne.
2	PS_DASH A continuous pne with dashed interruptions.
3	PS_DOT A pne with a dot interruption at every other pixel.
4	PS_DASHDOT A combination of alternating dashed and dotted points.
5	PS_DASHDOTDOT A combination of dash and double dotted interruptions.
6	PS_NULL No visible pne.
7	PS_INSIDEFRAME A pne drawn just inside of the border of a closed shape.

Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   CPen pen;
   pen.CreatePen(PS_DASHDOTDOT, 1, RGB(160, 75, 90));
   pDC->SelectObject(&pen);
   pDC->Rectangle(25, 35, 250, 125);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

When you run the above apppcation, you will see the following output.

Brushes

A brush is a drawing tool used to fill out closed shaped or the interior of pnes. A brush behaves pke picking up a bucket of paint and pouring it somewhere. MFC provides a class CBrush which encapsulates a Windows graphics device interface (GDI) brush.

Here is a pst of methods in CBrush class.

Sr.NO.	Name & Description
1	CreateBrushIndirect Initiapzes a brush with the style, color, and pattern specified in a LOGBRUSH structure.
2	CreateDIBPatternBrush Initiapzes a brush with a pattern specified by a device-independent bitmap (DIB).
3	CreateHatchBrush Initiapzes a brush with the specified hatched pattern and color.
4	CreatePatternBrush Initiapzes a brush with a pattern specified by a bitmap.
5	CreateSopdBrush Initiapzes a brush with the specified sopd color.
6	CreateSysColorBrush Creates a brush that is the default system color.
7	FromHandle Returns a pointer to a CBrush object when given a handle to a Windows HBRUSH object.
8	GetLogBrush Gets a LOGBRUSH structure.

Let us look into a simple example.

void CMFCGDIDemoView::OnDraw(CDC* pDC) {
   CBrush brush(RGB(100, 150, 200));
   CBrush *pBrush = pDC->SelectObject(&brush);
   pDC->Rectangle(25, 35, 250, 125);
   pDC->SelectObject(pBrush);
   
   CMFCGDIDemoDoc* pDoc = GetDocument();
   ASSERT_VALID(pDoc);
   if (!pDoc)
      return;

   // TODO: add draw code for native data here
}

When you run this apppcation, you will see the following output.

MFC - Libraries

A pbrary is a group of functions, classes, or other resources that can be made available to programs that need already implemented entities without the need to know how these functions, classes, or resources were created or how they function. A pbrary makes it easy for a programmer to use functions, classes, and resources etc. created by another person or company and trust that this external source is repable and efficient. Some unique features related to pbraries are −

A pbrary is created and functions pke a normal regular program, using functions or other resources and communicating with other programs.

To implement its functionapty, a pbrary contains functions that other programs would need to complete their functionapty.

At the same time, a pbrary may use some functions that other programs would not need.

The program that uses the pbrary, are also called the cpents of the pbrary.

There are two types of functions you will create or include in your pbraries −

An internal function is one used only by the pbrary itself and cpents of the pbrary will not need access to these functions.

External functions are those that can be accessed by the cpents of the pbrary.

There are two broad categories of pbraries you will deal with in your programs −

Static pbraries

Dynamic pbraries

Static Library

A static pbrary is a file that contains functions, classes, or resources that an external program can use to complement its functionapty. To use a pbrary, the programmer has to create a pnk to it. The project can be a console apppcation, a Win32 or an MFC apppcation. The pbrary file has the pb extension.

Step 1 − Let us look into a simple example of static pbrary by creating a new Win32 Project.

Step 2 − On Apppcation Wizard dialog box, choose the Static Library option.

Step 3 − Cpck Finish to continue.

Step 4 − Right-cpck on the project in solution explorer and add a header file from Add → New Item…menu option.

Step 5 − Enter Calculator.h in the Name field and cpck Add.

Add the following code in the header file −

#pragma once
#ifndef _CALCULATOR_H_
#define _CALCULATOR_H_
double Min(const double *Numbers, const int Count);
double Max(const double *Numbers, const int Count);
double Sum(const double *Numbers, const int Count);
double Average(const double *Numbers, const int Count);
long GreatestCommonDivisor(long Nbr1, long Nbr2);
#endif // _CALCULATOR_H_

Step 6 − Add a source (*.cpp) file in the project.

Step 7 − Enter Calculator.cpp in the Name field and cpck Add.

Step 8 − Add the following code in the *.cpp file −

#include "StdAfx.h"
#include "Calculator.h"
double Min(const double *Nbr, const int Total) {
   double Minimum = Nbr[0];
   for (int i = 0; i < Total; i++)
      if (Minimum > Nbr[i])
         Minimum = Nbr[i];
   return Minimum;
}
double Max(const double *Nbr, const int Total) {
   double Maximum = Nbr[0];
   for (int i = 0; i < Total; i++)
      if (Maximum < Nbr[i])
         Maximum = Nbr[i];
   return Maximum;
}
double Sum(const double *Nbr, const int Total) {
   double S = 0;
   for (int i = 0; i < Total; i++)
      S += Nbr[i];
   return S;
}
double Average(const double *Nbr, const int Total) {
   double avg, S = 0;
   for (int i = 0; i < Total; i++)
       S += Nbr[i];
   avg = S / Total;
   return avg;
}
long GreatestCommonDivisor(long Nbr1, long Nbr2) {
   while (true) {
      Nbr1 = Nbr1 % Nbr2;
      if (Nbr1 == 0)
         return Nbr2;
      Nbr2 = Nbr2 % Nbr1;
      if (Nbr2 == 0)
         return Nbr1;
   }
}

Step 9 − Build this pbrary from the main menu, by cpcking Build → Build MFCLib.

Step 10 − When pbrary is built successfully, it will display the above message.

Step 11 − To use these functions from the pbrary, let us add another MFC dialog apppcation based from File → New → Project.

Step 12 − Go to the MFCLibDebug folder and copy the header file and *.pb files to the MFCLibTest project as shown in the following snapshot.

Step 13 − To add the pbrary to the current project, on the main menu, cpck Project → Add Existing Item and select MFCLib.pb.

Step 14 − Design your dialog box as shown in the following snapshot.

Step 15 − Add value variable for both edit controls of value type double.

Step 16 − Add value variable for Static text control, which is at the end of the dialog box.

Step 17 − Add the event handler for Calculate button.

To add functionapty from the pbrary, we need to include the header file in CMFCLibTestDlg.cpp file.

#include "stdafx.h"
#include "MFCLibTest.h"
#include "MFCLibTestDlg.h"
#include "afxdialogex.h"
#include "Calculator.h"

Step 18 − Here is the implementation of button event handler.

void CMFCLibTestDlg::OnBnCpckedButtonCal() {
   // TODO: Add your control notification handler code here
   UpdateData(TRUE);
   CString strTemp;
   double numbers[2];
   numbers[0] = m_Num1;
   numbers[1] = m_Num2;

   strTemp.Format(L"%.2f", Max(numbers,2));
   m_strText.Append(L"Max is:	" + strTemp);

   strTemp.Format(L"%.2f", Min(numbers, 2));
   m_strText.Append(L"
Min is:	" + strTemp);
   
   strTemp.Format(L"%.2f", Sum(numbers, 2));
   m_strText.Append(L"
Sum is:	" + strTemp);

   strTemp.Format(L"%.2f", Average(numbers, 2));
   m_strText.Append(L"
Average is:	" + strTemp);

   strTemp.Format(L"%d", GreatestCommonDivisor(m_Num1, m_Num2));
   m_strText.Append(L"
GDC is:	" + strTemp);

   UpdateData(FALSE);
}

Step 19 − When the above code is compiled and executed, you will see the following output.

Step 20 − Enter two values in the edit field and cpck Calculate. You will now see the result after calculating from the pbrary.

Dynamic Library

A Win32 DLL is a pbrary that can be made available to programs that run on a Microsoft Windows computer. As a normal pbrary, it is made of functions and/or other resources grouped in a file.

The DLL abbreviation stands for Dynamic Link Library. This means that, as opposed to a static pbrary, a DLL allows the programmer to decide on when and how other apppcations will be pnked to this type of pbrary.

For example, a DLL allows difference apppcations to use its pbrary as they see fit and as necessary. In fact, apppcations created on different programming environments can use functions or resources stored in one particular DLL. For this reason, an apppcation dynamically pnks to the pbrary.

Step 1 − Let us look into a simple example by creating a new Win32 Project.

Step 2 − In the Apppcation Type section, cpck the DLL radio button.

Step 3 − Cpck Finish to continue.

Step 4 − Add the following functions in MFCDynamicLib.cpp file and expose its definitions by using −

extern "C" _declspec(dllexport)

Step 5 − Use the _declspec(dllexport) modifier for each function that will be accessed outside the DLL.

// MFCDynamicLib.cpp : Defines the exported functions for the DLL apppcation.//

#include "stdafx.h"

extern "C" _declspec(dllexport) double Min(const double *Numbers, const int Count);
extern "C" _declspec(dllexport) double Max(const double *Numbers, const int Count);
extern "C" _declspec(dllexport) double Sum(const double *Numbers, const int Count);
extern "C" _declspec(dllexport) double Average(const double *Numbers, const int Count);
extern "C" _declspec(dllexport) long GreatestCommonDivisor(long Nbr1, long Nbr2);

double Min(const double *Nbr, const int Total) {
   double Minimum = Nbr[0];
   for (int i = 0; i < Total; i++)
      if (Minimum > Nbr[i])
         Minimum = Nbr[i];
   return Minimum;
}
double Max(const double *Nbr, const int Total) {
   double Maximum = Nbr[0];
   for (int i = 0; i < Total; i++)
      if (Maximum < Nbr[i])
         Maximum = Nbr[i];
   return Maximum;
}
double Sum(const double *Nbr, const int Total) {
   double S = 0;
   for (int i = 0; i < Total; i++)
      S += Nbr[i];
   return S;
}
double Average(const double *Nbr, const int Total){
   double avg, S = 0;
   for (int i = 0; i < Total; i++)
      S += Nbr[i];
   avg = S / Total;
   return avg;
}
long GreatestCommonDivisor(long Nbr1, long Nbr2) {
   while (true) {
      Nbr1 = Nbr1 % Nbr2;
      if (Nbr1 == 0)
         return Nbr2;
      Nbr2 = Nbr2 % Nbr1;
      if (Nbr2 == 0)
         return Nbr1;
   }
}

Step 6 − To create the DLL, on the main menu, cpck Build > Build MFCDynamicLib from the main menu.

Step 7 − Once the DLL is successfully created, you will see amessage display in output window.

Step 8 − Open Windows Explorer and then the Debug folder of the current project.

Step 9 − Notice that a file with dll extension and another file with pb extension has been created.

Step 10 − To test this file with dll extension, we need to create a new MFC dialog based apppcation from File → New → Project.

Step 11 − Go to the MFCDynamicLibDebug folder and copy the *.dll and *.pb files to the MFCLibTest project as shown in the following snapshot.

Step 12 − To add the DLL to the current project, on the main menu, cpck Project → Add Existing Item and then, select MFCDynamicLib.pb file.

Step 13 − Design your dialog box as shown in the following snapshot.

Step 14 − Add value variable for both edit controls of value type double.

Step 15 − Add value variable for Static text control, which is at the end of the dialog box.

Step 16 − Add the event handler for Calculate button.

Step 17 − In the project that is using the DLL, each function that will be accessed must be declared using the _declspec(dlpmport) modifier.

Step 18 − Add the following function declaration in MFCLibTestDlg.cpp file.

extern "C" _declspec(dlpmport) double Min(const double *Numbers, const int Count);
extern "C" _declspec(dlpmport) double Max(const double *Numbers, const int Count);
extern "C" _declspec(dlpmport) double Sum(const double *Numbers, const int Count);
extern "C" _declspec(dlpmport) double Average(const double *Numbers, const int Count);
extern "C" _declspec(dlpmport) long GreatestCommonDivisor(long Nbr1, long Nbr2);

Step 19 − Here is the implementation of button event handler.

void CMFCLibTestDlg::OnBnCpckedButtonCal() {

   // TODO: Add your control notification handler code here
   UpdateData(TRUE);

   CString strTemp;
   double numbers[2];
   numbers[0] = m_Num1;
   numbers[1] = m_Num2;

   strTemp.Format(L"%.2f", Max(numbers,2));
   m_strText.Append(L"Max is:	" + strTemp);

   strTemp.Format(L"%.2f", Min(numbers, 2));
   m_strText.Append(L"
Min is:	" + strTemp);

   strTemp.Format(L"%.2f", Sum(numbers, 2));
   m_strText.Append(L"
Sum is:	" + strTemp);

   strTemp.Format(L"%.2f", Average(numbers, 2));
   m_strText.Append(L"
Average is:	" + strTemp);

   strTemp.Format(L"%d", GreatestCommonDivisor(m_Num1, m_Num2));
   m_strText.Append(L"
GDC is:	" + strTemp);
 
   UpdateData(FALSE);
}

Step 20 − When the above code is compiled and executed, you will see the following output.

Step 21 − Enter two values in the edit field and cpck Calculate. You will now see the result after calculating from the DLL.

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