/**********************************
  File:  hw2p3.c

calculate the factorial.

***********************************/


#include <stdio.h>
#include "simpio.h"

void main()
{
  int n=0,i=0;
  int product = 1;       /* keeps track of current product */

  printf("Enter an integer n: ");
  n = GetInteger();

  if (n < 0)             /* n is negative, factorial undefined */
    printf("Error, factorial undefined for %d\n", n);
  else {                 /* n is >= 0 */
    for (i=1; i<=n; i++) /* loop n times */
      product *= i;
    printf("%d factorial = %d\n", n, product);    
  }
}