Opgaveløsning:
Ligefrem programmering af 'største fælles divisor'

#include <stdio.h>
#include <stdlib.h>

int main(void) {
  int i, j, small, large, n;

  do {
    printf("Enter two non-negative integers: ");
    scanf("%d %d", &i, &j);
  
    small = i <= j ? i : j;
    large = i <= j ? j : i;
  
    if (small < 0 || large < 0)
      printf("Bye");
    else if (small == 0 && large == 0)
      printf("We cannot find gcd in case both inputs are zero\n");
    else if (small == 0)
      printf("GCD of 0 and %d is %d\n", large, large);
    else {                       
      /* small > 0 && large > 0 */ 
  
      n = small;
      while((small % n != 0 || large % n != 0) && (n >= 2)){
        --n;
      }
  
      /* (small % n == 0 && large % n == 0)  || (n == 1) */
  
      printf("GCD of %d and %d is %d\n", large, small, n);
    }
  } while (i >= 0 && j >= 0);

  return EXIT_SUCCESS;
}