/*
** primefactor.c: produce the prime factorization of a given number
**	partial solution to hw#8
**   -- written by Jeff Tian, 3/2/99.     
*/

#include <stdio.h>
#include <math.h>
#include <ctype.h>
#include "genlib.h"
#include "simpio.h"

void PrimeFactor(int x);

main()
{
   int n; 
   char c='y';

   printf("This program produces prime factorization for input numbers.\n\n");

   while (c == 'y' || c == 'Y')
   {
      printf("Please enter a positive integer: ");
      n = GetInteger();
      while (n <= 0 )
      {
         printf("You need to enter a positive integer. Try again: ");
         n = GetInteger();
      }
      PrimeFactor(n);
      printf("\nWould you like to try another number [y/n] ? ");
      while (isspace(c = getchar()));
      while (getchar() != '\n');
   }
}

/*
** PrimeFactor() -- an efficient function for prime factorization
*/ 

void
PrimeFactor(int x)
{
   int i=2, limit;

   printf("The prime factors for %d is:\n", x);
   limit = sqrt(x);
   while (i <= limit ) 
   {
      if(x%i == 0)
      {
         printf("%d X ", i);
         x = x/i;
         limit = sqrt(x);
      }
      else 
      {
         i++;
      }
   }
   printf("%d\n", x);
}