"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:\n"); 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