C Program to Reverse a Number - Iterative Approach

Write a C program to reverse a number. In this tutorial, We are going to write a c code which takes an input number and print the reverse of that number.


Program to Reverse a number using Recursion

Algorithm to Reverse a Number

Before solving this problem, let's discuss and understand the approach.


1. Take an input number from a user.

2. Run a while until the num is greater than zero and reverse that number.

 while(num > 0) {

          temp = num%10;   // Store the result in temp variable

          rev = (rev*10)+temp;

          num = num/10; 
        
      }
 

Explanation -  

 Suppose, An input number is 243. 

 While loop condition is true, as num is 243 

 rev = 0 * 10 + 3; 

 num = 24; 

 Now num is 24 still while loop condition is true, 

 rev = 3*10 + 4; 

 num = 2; 

 Now num is 2, again while loop is executed, 

 rev = 34 * 10 + 2 

 num = 0; 

 Now number is zero while loop will break

Program to Reverse a String

C Program to Reverse a Number

#include <stdio.h>

int main(void) {
 
    int num, temp, rev=0;

    printf("Enter a number");
    scanf("%d", &num);

 
    while(num != 0){

       temp = num % 10;
       rev  = (rev*10)+ temp;
       num  = num/10;

    }

    printf("Reverse of a input number is  %d", rev);


    return 0;
}

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