C Program to reverse a given number using Recursive function

"Recursive function" is something which calls itself again in the body of the function.

For example,

• A function fact ( ), which computes the factorial of an integer ‘N’, which is the product of all whole numbers from 1 to N.

• fact ( ) with an argument of 1 (or) 0, the function returns 1. otherwise, it returns n*fact (n-1), this happens until ‘n’ equals 1.

Fact (5) =5* fact (4)
   =5*4*3* fact (3)
   =5*4*3*2* fact (2)
   =5*4*3*2*1 fact (1)
   =5*4*3*2*1
   = 120.

Example

Following is the C program for use of recursive function to reverse a number −

#include<stdio.h>
main ( ){
   int n,f;
   int fact (int);
   clrscr ( );
   printf ("enter a number");
   scanf ("%d", &n);
   f= fact (n);
   printf (factorial value = %d",f);
}
int fact (int n){
   int f;
   if ( ( n==1) || (n==0))
      return 1;
   else
      f= n*fact (n-1);
   return f;
}

Output

The output is given below −

Enter a number 5
Factorial value = 120

Given below is another C Program to reverse a given number using Recursive function −

#include<stdio.h>
int sum=0,rem;
int main(){
   int num,revNum;
   printf("enter number:
");
   scanf("%d",&num);
   revNum=revNumFunction(num);//calling function to reverse the given number
   printf("the number after reverse :%d",revNum);
   return 0;
}
revNumFunction(int num){
   if(num){
      rem=num%10;
      sum=sum*10+rem;
      revNum(num/10);
   }
   else
      return sum;
}

Output

The output is as follows −

enter number: 1357
the number after reverse is :7531