Recursion In C Program

Recursion In C Program

In this tutorial, We will learn about recursion in C programming language.

Introduction

The process in which a function calls itself directly or indirectly is called recursion and the corresponding function is called as a recursive function.

• Base Condition: In Recursion: in a recursive program base case provide the solution to the smallest problem
• Expression: In a recursive program we write an expression for the bigger problem in term of smaller problems

Example: Calculate the Factorial of n.

Factorial(n) = (n) x (n-1) x ... x 1

• Base Condition: the factorial of smallest number i.e 1 is 1 hence base condition is if n equal to 1 factorial will be 1
• Expression:  Suppose we want to calculate factorial of n and we already know the factorial of n-1 we can calculate factorial of n by multiplying n to the factorial of n -1. for  example if we want to calculate factorial of 5 and we already know factorial of 4 we can calculate factorial of 5 by multiplying 5 into factorial of 4 i.e factorial(5) =  5 x factorial(4) = 5 x 24 = 120 hence here expression will be factorial(n) = n x factorial(n-1)

 #include<stdio.h>  
 int factorial(int n) {  
      // base condition  
      if (n==1) {   
           return 1;        
      }   
      // expression  
      return n*factorial(n-1);  
 }  
 int main() {  
      int n;  
      printf("Enter an integer: ");  
      scanf("%d", &n);  
      printf("Factorial of %d is %d\n", n, factorial(n));  
      return 0;  
 }  

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