C program to find reverse of a number

Write a C program to input a number from user and find reverse of the given number using for loop. How to find reverse of any number using loop in C program. Logic to find reverse of a number in C programming.

Example

Input

Input number: 12345

Output

Reverse of 12345 = 54321

C program to find reverse of a number using loop

Required knowledge

Basic C programming, While loop

Logic to find reverse of a number

Step by step descriptive logic to find reverse of a number.

  1. Input a number from user to find reverse. Store it in some variable say num.
  2. Declare and initialize another variable to store reverse of num, say reverse = 0.
  3. Extract last digit of the given number by performing modulo division. Store the last digit to some variable say lastDigit = num % 10.
  4. Increase the place value of reverse by one. To increase place value multiply reverse variable by 10 i.e. reverse = reverse * 10.
  5. Add lastDigit to reverse i.e. reverse = reverse + lastDigit.
  6. Since last digit of num is processed hence, remove last digit of num. To remove last digit divide num by 10 i.e. num = num / 10.
  7. Repeat step 3 to 6 till num is not equal to (or greater than) zero.

Let us implement the above logic in C program.

Program to find reverse of a number

/**
 * C program to find reverse of a number
 */

#include <stdio.h>

int main()
{
    int num, reverse = 0;

    /* Input a number from user */
    printf("Enter any number to find reverse: ");
    scanf("%d", &num);

    /* Repeat the till 'num' becomes 0 */
    while(num != 0)
    {
        /* 
         * Increase place value of reverse and 
         * add last digit to reverse 
         */
        reverse = (reverse * 10) + (num % 10);

        /* Remove last digit from 'num' */
        num /= 10;
    }

    printf("Reverse = %d", reverse);

    return 0;
}

Take a step forward and learn this program using recursive approach.

Learn more - Program to find reverse of any number using recursion.

Output

Enter any number to find reverse: 12345
Reverse = 54321

Happy coding 😉

About Pankaj

Pankaj Prakash is the founder, editor and blogger at Codeforwin. He loves to learn new techs and write programming articles especially for beginners. He works at Vasudhaika Software Sols. as a Software Design Engineer and manages Codeforwin. In short Pankaj is Web developer, Blogger, Learner, Tech and Music lover.

Follow on: Facebook | Twitter | Google | or

Comments and discussion
Have a doubt, write here. I will help my best.
Before commenting you must escape your source code before commenting. Paste your source code inside
<pre><code> ----Your Source Code---- </code></pre>