Thread: The greatest common divisor (GCD) help..

I made this program (using C not C++):

Code:

#include<stdio.h>
int num1, num2;
int main() {
	printf("Type in two numbers: ");
	scanf("%d %d", &num1, &num2);
	while (num1!=num2){
		if (num1>num2){
			num1=num1-num2;
		} else {
		num2=num2-num1;
		}
 }
	printf("The GCD is: \n%d");
}

but it's not working correctly. I'm suppose to use 2 integers and like 21 and 15 and then I have to get the GCD, and the GCD should be 3 out of 21 and 15 but in my programme it display 2293624 for any 2 numbers.
Can someone please explain what did I do wrong and how can I fix it
Thanks

print the result.
u havent printed anything.

2 questions i want to ask to you damha:
1. the program seems to be ok. but whats the mathetical reason behind it. i did the same program but it was a longer one(not the source code, but the process).
2.what compiler are you using?