C Program to Find GCD or HCF of Two Numbers using For Loop

  • Write a C program to find GCD (Greatest Common Divisor) of two numbers using for loop.
  • Wap in C to find HCF (Highest Common Factor) of two numbers.

Required Knowledge

The highest common factor (HCF) of two or more integers, is the largest positive integer that divides the numbers without a remainder. HCF is also known as greatest common divisor (GCD) or greatest common factor(GCF)

Algorithm to find GCD of two numbers
Let, A and B are two numbers.
  • Find minimum of A and B. Let A < B.
  • Find the largest number between 1 to A, which divides A and B both completely.

C program to find gcd of two numbers using for loop

#include <stdio.h>  

int getMinimum(int a, int b){
    if(a >= b)
        return b;
    else 
        return a;
}

int main() {  
    int a, b, min, counter, gcd = 1;  
    /* 
     * Take two numbers as input from user  
     */  
    printf("Enter two numbers\n");  
    scanf("%d %d", &a, &b);  
  
    min = getMinimum(a, b);
  
    for(counter = 1; counter <= min; counter++) {  
        /* 
         * Check, If counter divides both input number  
         */
        if(a%counter==0 && b%counter==0) {
            /* Update GCD to new larger value */ 
            gcd = counter;  
        }  
    }  
  
    printf("GCD of %d and %d = %d\n", a, b, gcd);
   
    return 0;  
}

Output
Enter two numbers
15 50
GCD of 15 and 50 = 5
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