C Program to Reverse an Array

In this tutorial, you will learn and get code about reversing of an array in C. Reverse of an array means

• First element becomes last and Last element becomes first
• Similarly second element becomes second last and Second last element becomes second
• and so on

For example, if given array is:

2 6 4 8

then its reverse will be

8 4 6 2

C Print Reverse of Array

Before reversing the array, let's first create a program that will receive 10 array elements and will print the array in reverse order.

To print the array elements in reverse order, start its indexing from last to the first. That is, if user has provided 10 array elements, then the array present at index number 9 will be printed first and the element present at index number 0 will be printed at last. In this way, array in reverse order gets printed as shown in the program given below:

#include<stdio.h>
#include<conio.h>
int main()
{
    int arr[10], i;
    printf("Enter any 10 elements: ");
    for(i=0; i<10; i++)
    {
        scanf("%d", &arr[i]);
    }
    printf("\nThe array elements in reverse order:\n");
    for(i=9; i>=0; i--)
    {
        if(i==0)
            printf("%d", arr[i]);
        else
            printf("%d, ", arr[i]);
    }
    getch();
    return 0;
}

The program given above was written under Code::Blocks IDE, therefore after successful build and run, here is its sample run:

Supply any 10 array elements and press ENTER key to see the given 10 array elements in reverse order as shown in the second snapshot of the sample run:

C Reverse an Array

Now let's modify the above program in a way that it will receive the size of an array say 5. Then will ask to enter 5 array elements. After receiving the array elements, this program will reverse the array and then prints the array on output. In previous program, we have printed the array in reverse order without actually reversing it

#include<stdio.h>
#include<conio.h>
int main()
{
    int arr[50], size, i, j, temp;
    printf("Enter array size: ");
    scanf("%d",&size);
    printf("Enter %d array elements: ", size);
    for(i=0; i<size; i++)
        scanf("%d",&arr[i]);
    j=i-1;  // now j will point to the last element
    i=0;   //  and i will be point to the first element
    while(i<j)
    {
        temp=arr[i];
        arr[i]=arr[j];
        arr[j]=temp;
        i++;
        j--;
    }
    printf("\nReverse of the Array is:\n");
    for(i=0; i<size; i++)
        printf("%d ",arr[i]);
    getch();
    return 0;
}

The program was written under Code::Blocks IDE, here is the first snapshot of the sample run:

Supply the size of the array say 5 and then enter any 5 array elements, press ENTER key to reverse the array. And print its reverse as shown in the second snapshot of the sample run:

Program Explained

• Receive array size say 5
• Then receive 5 array elements
• Using while loop, as the size of the array here is 5 therefore the element present at last, that is the element present at 4^th index will be initialized to the 0^th index and the element present at 0^th index will be initialized to 4^th index, and then 3^rd will be initialized to 1^st and 1^st will be initialized to 3^rd and so on.
• In this way, we can reverse the array as shown in the above program
• Finally print the array after reversing

C Print Original Array and its Reverse

Let's create one more program that will receive the size and elements for an array. And will print the array elements in original and reverse order:

#include<stdio.h>
#include<conio.h>
int main()
{
    int arr[100], i, limit;
    printf("How many elements you want to store inside the array: ");
    scanf("%d", &limit);
    printf("Enter any %d elements: ", limit);
    for(i=0; i<limit; i++)
    {
        scanf("%d", &arr[i]);
    }
    printf("\nThe array elements are:\n");
    for(i=0; i<limit; i++)
    {
        if(i==(limit-1))
            printf("%d", arr[i]);
        else
            printf("%d, ", arr[i]);
    }
    printf("\nNow the array elements in reverse order:\n");
    for(i=(limit-1); i>=0; i--)
    {
        if(i==0)
            printf("%d", arr[i]);
        else
            printf("%d, ", arr[i]);
    }
    getch();
    return 0;
}

Here is the sample run:

Same Program in Other Languages

• C++ Reverse Array
• Java Reverse Array

C Online Test