/* File: gcd2.c
   Euclid's aglorithm for Greatest Common Divisor
*/

#include <stdio.h>

int gcd(int m, int n) {
   int r ;

   printf("gcd: m = %d, n = %d\n", m, n) ;
   r = m % n ;
   if (r == 0)
      return n ;
   else
      return gcd(n,r) ;
}


main(int argc, char *argv[]) {

   long m, n, answer ;
   int r1, r2 ;

   if (argc !=3) {
      printf("Wrong number of arguments!\n") ;
      exit() ;
   }

   r1 = sscanf(argv[1],"%ld", &m) ;
   if (r1 != 1) {
      printf("%s not an integer!\n", argv[1]) ;
      exit() ;
   }

   r2 = sscanf(argv[2],"%ld", &n) ;
   if (r2 != 1) {
      printf("%s not an integer!\n", argv[2]) ;
      exit() ;
   }

   if (n <= 0 || m <= 0) {
      printf("numbers must be positive\n") ;
      exit() ;
   }

   answer = gcd(m,n) ;
   printf("The GCD of %d and %d is %d\n",
	   m, n, answer ) ;
}