gcd

gcd.c

/* gcd.c
 * run `make gcd` */
#include <stdio.h>
#include <stdlib.h>

long gcd (long a, long b) {
	ldiv_t qr;

	while (b != 0) {
		qr = ldiv(a, b);
		a = b;
		b = qr.rem;
	}

	return a;
}

int main(int argc, char *argv[]) {
	if (argc != 3) {
		printf ("usage: %s [a] [b]\n", argv[0]);
		exit(1);
	}

	long a = atol(argv[1]);
	long b = atol(argv[2]);
	long val = gcd (a, b);
	printf("gcd(%ld, %ld) = %ld\n", a, b, val);
}