/*--------------------------------------------------------------------*/
/* testintmath.c (Version 2)                                          */
/* Author: Bob Dondero                                                */
/*--------------------------------------------------------------------*/

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

/*--------------------------------------------------------------------*/
/* Function declarations                                              */
/*--------------------------------------------------------------------*/

/* Return the greatest common divisor of positive integers iFirst and
   iSecond. */
static int gcd(int iFirst, int iSecond);

/* Return the least common multiple of positive integers iFirst and
   iSecond. */
static int lcm(int iFirst, int iSecond);

/*--------------------------------------------------------------------*/
/* Function definitions                                               */
/*--------------------------------------------------------------------*/

/* Read two positive integers from stdin. Return EXIT_FAILURE if stdin
   contains bad data and write an error message to stderr. Otherwise
   compute the greatest common divisor and least common multiple of
   the two positive integers, write those two values to stdout, and
   return 0. */

int main(void)
{
   int i1;
   int i2;
   int iGcd;
   int iLcm;
   int iScanfReturn;

   printf("Enter the first positive integer:\n");
   iScanfReturn = scanf("%d", &i1);
   if ((iScanfReturn != 1) || (i1 <= 0))
   {
      fprintf(stderr, "Error: Not a positive integer.\n");
      exit(EXIT_FAILURE);
   }

   printf("Enter the second positive integer:\n");
   iScanfReturn = scanf("%d", &i2);
   if ((iScanfReturn != 1) || (i2 <= 0))
   {
      fprintf(stderr, "Error: Not a positive integer.\n");
      exit(EXIT_FAILURE);
   }

   iGcd = gcd(i1, i2);
   iLcm = lcm(i1, i2);

   printf("The greatest common divisor of %d and %d is %d.\n",
      i1, i2, iGcd);
   printf("The least common multiple of %d and %d is %d.\n",
      i1, i2, iLcm);

   return 0;
}

/*--------------------------------------------------------------------*/

static int gcd(int iFirst, int iSecond)
{
   int iTemp;

   /* Use Euclid's algorithm. */

   while (iSecond != 0)
   {
      iTemp = iFirst % iSecond;
      iFirst = iSecond;
      iSecond = iTemp;
   }

   return iFirst;
}

/*--------------------------------------------------------------------*/

static int lcm(int iFirst, int iSecond)
{
   return (iFirst / gcd(iFirst, iSecond)) * iSecond;
}