Program to find factorial of a number in c using recursion

Here we are going to write a program to find factorial of a number in c using recursion. Earlier we have done this program in two ways. C Program to find factorial of a number and C Program to find factorial of a number using function. Now we will do it using recursion.

Factorial Number: A factorial number is the product of all the number from 1 to the given number.

We represent factorial by '!' .

Example - 

n! = n x (n-1) x (n-2) x ....... x 1

5! = 5 x 4 x 3 x 2 x 1 = 120

4! = 4 x 3 x 2 x 1 = 24

3! = 3 x 2 x 1 = 6

There is one exceptional case in factorial and that you must know. Factorial of 0 i.e., 0! = 1, not 0.

What is Recursion?

Recursion occurs when a function calls itself within a function as a result it is called repeatedly. It solves smaller subproblems of original problem. 

Now lets do the program. But before going down I will suggest you to first try it on your own and then see the solution.

Program to find factorial of a number in c using recursion 

#include <stdio.h>

int fact(n){
   if(n==0) return 1;
   else if(n==1) return 1;
   else return n*fact(n-1);
}

int main(){
   int n;
   printf("Enter a number: ");
   scanf("%d",&n);
   int f=fact(n);
   printf("Factorial : %d",f);
   return 0;
}

Output

Enter a number: 5
Factorial : 120

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