Defining an array

1. Without specifying the size of the array:

   int arr[] = {1, 2, 3};

   Here, we can leave the square brackets empty, although the array cannot be left empty in this case. It must have elements in it.

2. With specifying the size of the array:

   int arr[3];
   arr[0] = 1, arr[1] = 2, arr[2] = 3;

Accessing an array element

An element in an array can easily be accessed through its index number. An index number is a special type of number which allows us to access variables of arrays. Index number provides a method to access each element of an array in a program. This must be remembered that the index number starts from 0 and not one.

Example:

#include <iostream>
using namespace std;
 
int main()
{
    int arr[] = {1, 2, 3};
    cout << arr[1] << endl;
}

Output:

2

Changing an array element

An element in an array can be overwritten using its index number.

Example:

#include <iostream>
using namespace std;
 
int main()
{
    int arr[] = {1, 2, 3};
    arr[2] = 8; // changing the element on index 2
    cout << arr[2] << endl;
}

Output:

8