Write a C Program to find HCF of Number using Recursion

Recursion : :

• Recursion is the process of repeating items in a self-similar way. In programming languages, if a program allows you to call a function inside the same function, then it is called a recursive call of the function.

• The C programming language supports recursion, i.e., a function to call itself. But while using recursion, programmers need to be careful to define an exit condition from the function, otherwise it will go into an infinite loop.

• Recursive functions are very useful to solve many mathematical problems, such as calculating the factorial of a number, generating Fibonacci series, etc.

Problem : :

The following C program using recursion finds the HCF of two entered integers. The HCF stands for Highest Common Factor.

Below is the source code for C Program to find HCF of Number using Recursion which is successfully compiled and run on Windows System to produce desired output as shown below :

SOURCE CODE : :

/*  C Program to find HCF of Number using Recursion  */


#include <stdio.h>
 
int hcf(int, int);
 
int main()
{
    int a, b, result;
 
    printf("Enter the two numbers to find their HCF: ");
    scanf("%d%d", &a, &b);
    result = hcf(a, b);
    printf("The HCF of %d and %d is %d.\n", a, b, result);
}
 
int hcf(int a, int b)
{
    while (a != b)
    {
        if (a > b)
        {
            return hcf(a - b, b);
        }
        else
        {
            return hcf(a, b - a);
        }
    }
    return a;
}

Output : :

***************** OUTPUT **********************


**************** FIRST RUN ********************

Enter the two numbers to find their HCF:
12
72
The HCF of 12 and 72 is 12.

**************** SECOND RUN ********************

Enter the two numbers to find their HCF:
35
65
The HCF of 35 and 65 is 5.