- VB.Net - Event Handling
- VB.Net - Advanced Forms
- VB.Net - Dialog Boxes
- VB.Net - Basic Controls
- VB.Net - File Handling
- VB.Net - Exception Handling
- VB.Net - Classes & Objects
- VB.Net - Subs
- VB.Net - Functions
- VB.Net - Collections
- VB.Net - Arrays
- VB.Net - Date & Time
- VB.Net - Strings
- VB.Net - Loops
- VB.Net - Decision Making
- VB.Net - Operators
- VB.Net - Directives
- VB.Net - Statements
- VB.Net - Modifiers
- VB.Net - Constants
- VB.Net - Variables
- VB.Net - Data Types
- VB.Net - Basic Syntax
- VB.Net - Program Structure
- VB.Net - Environment Setup
- VB.Net - Overview
- VB.Net - Home
VB.Net Advanced Tutorial
- VB.Net - Web Programming
- VB.Net - XML Processing
- VB.Net - Send Email
- VB.Net - Excel Sheet
- VB.Net - Database Access
- VB.Net - Regular Expressions
VB.Net Useful Resources
Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
VB.Net - Constants and Enumerations
The constants refer to fixed values that the program may not alter during its execution. These fixed values are also called pterals.
Constants can be of any of the basic data types pke an integer constant, a floating constant, a character constant, or a string pteral. There are also enumeration constants as well.
The constants are treated just pke regular variables except that their values cannot be modified after their definition.
An enumeration is a set of named integer constants.
Declaring Constants
In VB.Net, constants are declared using the Const statement. The Const statement is used at module, class, structure, procedure, or block level for use in place of pteral values.
The syntax for the Const statement is −
[ < attributepst > ] [ accessmodifier ] [ Shadows ] Const constantpst
Where,
attributepst − specifies the pst of attributes appped to the constants; you can provide multiple attributes separated by commas. Optional.
accessmodifier − specifies which code can access these constants. Optional. Values can be either of the: Pubpc, Protected, Friend, Protected Friend, or Private.
Shadows − this makes the constant hide a programming element of identical name in a base class. Optional.
Constantpst − gives the pst of names of constants declared. Required.
Where, each constant name has the following syntax and parts −
constantname [ As datatype ] = initiapzer
constantname − specifies the name of the constant
datatype − specifies the data type of the constant
initiapzer − specifies the value assigned to the constant
For example,
The following statements declare constants. Const maxval As Long = 4999 Pubpc Const message As String = "HELLO" Private Const piValue As Double = 3.1415
Example
The following example demonstrates declaration and use of a constant value −
Module constantsNenum Sub Main() Const PI = 3.14149 Dim radius, area As Single radius = 7 area = PI * radius * radius Console.WriteLine("Area = " & Str(area)) Console.ReadKey() End Sub End Module
When the above code is compiled and executed, it produces the following result −
Area = 153.933
Print and Display Constants in VB.Net
VB.Net provides the following print and display constants −
Sr.No. | Constant & Description |
---|---|
1 |
vbCrLf Carriage return/pnefeed character combination. |
2 |
vbCr Carriage return character. |
3 | vbLf Linefeed character. |
4 | vbNewLine Newpne character. |
5 | vbNullChar Null character. |
6 | vbNullString Not the same as a zero-length string (""); used for calpng external procedures. |
7 | vbObjectError Error number. User-defined error numbers should be greater than this value. For example: Err.Raise(Number) = vbObjectError + 1000 |
8 | vbTab Tab character. |
9 | vbBack Backspace character. |
Declaring Enumerations
An enumerated type is declared using the Enum statement. The Enum statement declares an enumeration and defines the values of its members. The Enum statement can be used at the module, class, structure, procedure, or block level.
The syntax for the Enum statement is as follows −
[ < attributepst > ] [ accessmodifier ] [ Shadows ] Enum enumerationname [ As datatype ] memberpst End Enum
Where,
attributepst − refers to the pst of attributes appped to the variable. Optional.
accessmodifier − specifies which code can access these enumerations. Optional. Values can be either of the: Pubpc, Protected, Friend or Private.
Shadows − this makes the enumeration hide a programming element of identical name in a base class. Optional.
enumerationname − name of the enumeration. Required
datatype − specifies the data type of the enumeration and all its members.
memberpst − specifies the pst of member constants being declared in this statement. Required.
Each member in the memberpst has the following syntax and parts:
[< attribute pst >] member name [ = initiapzer ]
Where,
name − specifies the name of the member. Required.
initiapzer − value assigned to the enumeration member. Optional.
For example,
Enum Colors red = 1 orange = 2 yellow = 3 green = 4 azure = 5 blue = 6 violet = 7 End Enum
Example
The following example demonstrates declaration and use of the Enum variable Colors −
Module constantsNenum Enum Colors red = 1 orange = 2 yellow = 3 green = 4 azure = 5 blue = 6 violet = 7 End Enum Sub Main() Console.WriteLine("The Color Red is : " & Colors.red) Console.WriteLine("The Color Yellow is : " & Colors.yellow) Console.WriteLine("The Color Blue is : " & Colors.blue) Console.WriteLine("The Color Green is : " & Colors.green) Console.ReadKey() End Sub End Module
When the above code is compiled and executed, it produces the following result −
The Color Red is: 1 The Color Yellow is: 3 The Color Blue is: 6 The Color Green is: 4Advertisements