/* Program to find Greatest Common Factor of two number. */ Description : The greatest common divisor (GCD) of a set of integers is the largest integer that divides each integer in the set. It is also called Highest Common Factor. Program : copy #include<stdio.h> #include<conio.h> int gcd(int a,int b) { if(a==0) return b; return gcd(b%a,a); } void swap(int a,int b) { int temp; temp = a; a = b; b = temp; } void main() { int x,y; printf("Enter first number : "); scanf("%d",&x); printf("Enter second number : "); scanf("%d",&y); if(y>x) swap(x,y); printf("Greatest Common Factor of %d and %d is %d.",x,y,gcd(x,y)); getch(); } Output : ` tested in Turbo C 3.2 Written with ♥ from Mangesh. Related Post 1 C program to calculate factorial of given number. 2 C program to convert decimal number to binary number. 3 C program to find the G.C.D. of two number. Latest Post 1 C program to implement Queue using linked list. 2 C program for binary search tree (BST). 3 C program to search an element in linked list. 4 C program for postorder traversal in binary tree. 5 C program for preorder traversal in binary tree.