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

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

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

static int gcd(int iFirst, int iSecond);
static int lcm(int iFirst, int iSecond);

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

int main(void)

/* Read two positive integers from stdin, compute the greatest
   common divisor and least common multiple of the two numbers,
   and write those two values to stdout.  Return 0 if successful. */

{
   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)

/* Return the greatest common divisor of positive integers iFirst and
   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 the least common multiple of positive integers iFirst and
   iSecond. */

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