/* File: gcdlcm.c */
#include <stdio.h>
#include <stdlib.h>      /* Header file for srand and rand functions */
#include <time.h>                   /* Header file for time function */
#define COMPUTATIONS 8    /* Pairs of numbers to compute GCD and LCM */
#define MAXNUMB 1000                               /* Maximum number */

main()
{ int i, m, n, large, small, gcd, rem;
  long curtime, lcm;
  curtime = time(NULL);  /* Current time (in seconds since 1/1/1970) */
  printf("Current time is %ld\n\n", curtime);
  srand((unsigned int) curtime); /* Seed for random number generator */
  for (i=0 ; i < COMPUTATIONS ; i++) {
    m = rand() % MAXNUMB + 1;    /* Select 1st number in [1,MAXNUMB] */
    n = rand() % MAXNUMB + 1;    /* Select 2nd number in [1,MAXNUMB] */
    if (m > n) {                          /* Which number is larger? */
      large = m;                                      /* Larger is m */
      small = n;
    }
    else {
      large = n;                                      /* Larger is n */
      small = m;
    }
    while (small) {                          /* While small is not 0 */
      rem = large % small;          /* Find remainder of large/small */
      large = small;                  /* New large is previous small */
      small = rem;                   /* New small is remainder found */
    }
    gcd = large;    /* GCD of m and n equals to final value of large */
    lcm = (m*n)/gcd;                  /* LCM(m,n) * GCD(m,n) = m * n */
    printf("GCD(%3d,%3d) = %2d  LCM(%3d,%3d) = %6ld\n",
           m, n, gcd, m, n, lcm);
  }
}