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C++ Arrays
C++ provides a data structure, the array, which stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.
Instead of declaring inspanidual variables, such as number0, number1, ..., and number99, you declare one array variable such as numbers and use numbers[0], numbers[1], and ..., numbers[99] to represent inspanidual variables. A specific element in an array is accessed by an index.
All arrays consist of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element.
Declaring Arrays
To declare an array in C++, the programmer specifies the type of the elements and the number of elements required by an array as follows −
type arrayName [ arraySize ];
This is called a single-dimension array. The arraySize must be an integer constant greater than zero and type can be any vapd C++ data type. For example, to declare a 10-element array called balance of type double, use this statement −
double balance[10];
Initiapzing Arrays
You can initiapze C++ array elements either one by one or using a single statement as follows −
double balance[5] = {1000.0, 2.0, 3.4, 17.0, 50.0};
The number of values between braces { } can not be larger than the number of elements that we declare for the array between square brackets [ ]. Following is an example to assign a single element of the array −
If you omit the size of the array, an array just big enough to hold the initiapzation is created. Therefore, if you write −
double balance[] = {1000.0, 2.0, 3.4, 17.0, 50.0};
You will create exactly the same array as you did in the previous example.
balance[4] = 50.0;
The above statement assigns element number 5th in the array a value of 50.0. Array with 4th index will be 5th, i.e., last element because all arrays have 0 as the index of their first element which is also called base index. Following is the pictorial representaion of the same array we discussed above −
![Array Presentation](/cplusplus/images/array_presentation.jpg)
Accessing Array Elements
An element is accessed by indexing the array name. This is done by placing the index of the element within square brackets after the name of the array. For example −
double salary = balance[9];
The above statement will take 10th element from the array and assign the value to salary variable. Following is an example, which will use all the above-mentioned three concepts viz. declaration, assignment and accessing arrays −
#include <iostream> using namespace std; #include <iomanip> using std::setw; int main () { int n[ 10 ]; // n is an array of 10 integers // initiapze elements of array n to 0 for ( int i = 0; i < 10; i++ ) { n[ i ] = i + 100; // set element at location i to i + 100 } cout << "Element" << setw( 13 ) << "Value" << endl; // output each array element s value for ( int j = 0; j < 10; j++ ) { cout << setw( 7 )<< j << setw( 13 ) << n[ j ] << endl; } return 0; }
This program makes use of setw() function to format the output. When the above code is compiled and executed, it produces the following result −
Element Value 0 100 1 101 2 102 3 103 4 104 5 105 6 106 7 107 8 108 9 109
Arrays in C++
Arrays are important to C++ and should need lots of more detail. There are following few important concepts, which should be clear to a C++ programmer −
Sr.No | Concept & Description |
---|---|
1 | C++ supports multidimensional arrays. The simplest form of the multidimensional array is the two-dimensional array. |
2 | You can generate a pointer to the first element of an array by simply specifying the array name, without any index. |
3 | You can pass to the function a pointer to an array by specifying the array s name without an index. |
4 | C++ allows a function to return an array. |