C++ Program - Identify Pythagoras Triangle

// Pythagoras-03.cpp

/* Listing of right angle triangles with whole number sides e.g. 3 4 5
   Need only try possible values below Squareroot of side_1 sqaured + side_2 squared

   I want to treat triangle (3 4 5) as a duplicate of (4 3 5)
     Achieve this by only selecting results with side_1 > side_2

   Also need to remove multiples such as (6 8 10) (12 16 20)
     all multiples of (3 4 5).
   Do this by seeing if greatest common denominator > 1 by calling
     gcd with side-1 and side_2 to find their gcd and then call gcd
     again with this gcd and hyp.
     If this is 1 then combination is not a multiple
   gcd uses Euclidean method to find gcd.

   Virtual printer provides an alternative output source for printer
     redirecting to D:\\My Documents\\Temp\\VPRINTER.OUT.
   I use this as the console does not keep all of output in lon runs.
   You can comment it out if you wish.


*/
#include 
#include 
#include 
#include "D:\My Documents\Borland Studio Projects\mytools.h"
// #include "C:\Documents and Settings\Rod Talboys\My Documents\Borland Studio Projects\mytools.h"

void get_range (int& min, int& max);  //out
int gcd (int a, int b);               // in-out

void main()

{
  // Virtual printer
  // This file provides an alternative output source for printer
  ofstream vprn ("D:\\My Documents\\Temp\\VPRINTER.OUT");

  int max, min, side_1, side_2, hyp, count;
  int hypmax, hypmin;

  get_range (min, max);
  cout << "Pythagorean triangles between  " << min << " and " << max << endl;
  vprn << "Pythagorean triangles between  " << min << " and " << max << endl;

  count=0;

  for (side_1=min;side_1<=max;side_1++)
  {
    for (side_2=min;side_2<=max;side_2++)
    {
       // check if side_1*side_1 + side_2*side_2 is perfect square
       // establish  hypmin and hypmax
       if (side_1>side_2) (hypmin=side_1);
       else (hypmin=side_2);                                // removes surplus
       hypmax= floor(sqrt(side_1*side_1 + side_2*side_2));  // processing
       for (hyp=hypmin;hyp<=hypmax;hyp++)
       {
         if ((hyp*hyp==(side_1*side_1 + side_2*side_2))&& (side_1 < side_2))
         {
           if ((gcd ( hyp, gcd (side_1, side_2))) == 1)
           {
             cout << side_1 << " " << side_2 << " " << hyp << endl;
             vprn << side_1 << " " << side_2 << " " << hyp << endl;
             count++ ;
           }
         }
       }
    }
  }
  cout << "There are " << count <<" Pythagorean triangles between  " << min << " and " << max << endl;
  vprn << "There are " << count <<" Pythagorean triangles between  " << min << " and " << max << endl;
  system("PAUSE");
  return 0;
}

void get_range (int& min, int& max)  //out
{
  bool valid;      // valid for input and prime for prime number

  valid = false;            //  initialise values
  max = 0;

  while (!valid)
  {
    cout << "Enter min and max (less than 1,000) values for smaller sides: " << endl;
    cin  >> min >> max;
    if (max > min && max <= 1000)
      valid = true;
    else
      cout << " Invalid entry try again." << endl;
  }
}

int gcd (int a, int b)
// Use the Euclidean algorithm to calculate and
// return the greatest common divisor of a and b.
{
   int r;
   a = labs(a); b=labs(b);
   while (b>0)
      { r = a%b; a = b; b = r; }
   return a;
}