Thread: Code decoding

Hi Everyone,
I have this code for one of my programs and I am not sure what it does. It was given to me by my professor. It is suppose to simplify fractions. But it is messing up my program. In this program we use overloaded operators and Class objects. It is a fraction calculator program.
In my code, I add, subtract, multiply and divide the fractions and that part works fine. Then the not simplified fraction (the answer not the ones being added) is sent to this function to be simplified. For some reason it is not working properly after being sent to this function.
Please can someone explain this function to me so I can better understand what this function does and how it is affecting my code?

Thanks

Code:

void Rational::reduce(  )
{
   int largest, gcd = 1;  // greatest common divisor;

   largest = ( numerator > denominator ) ? numerator: denominator;

   for ( int loop = 2; loop <= largest; ++loop )
       if ( numerator % loop == 0 && denominator % loop == 0 )
          gcd = loop;

   numerator /= gcd;
   denominator /= gcd;
}

thats the thin, I am not sure why it does not work.
Here is my implementation of all of the functions.

Code:

#include <cstdlib>
#include <iostream> 
#include "rational.h"
using namespace std;

Rational::Rational( int n, int d )
{
   if (d)
   {
		numerator = n;
		denominator = d;
   }
   else
   {
		numerator = 1;
		denominator = 1;
   }
}
bool Rational::operator!=( const int num )
   { return !( numerator == num ); }

//Fraction reducer function definition
void Rational::reduce(  )
{
   int largest, gcd = 1;  // greatest common divisor;

   largest = ( numerator > denominator ) ? numerator: denominator;

   for ( int loop = 2; loop <= largest; ++loop )
       if ( numerator % loop == 0 && denominator % loop == 0 )
          gcd = loop;

   numerator /= gcd;
   denominator /= gcd;
}

//Input operator function definition
istream &operator>> (istream &in, Rational &pFractB)
{
	char slash;
	
	in >> pFractB.numerator >> slash >> pFractB.denominator;
	
	return in;
}

//Output operator function defintion
ostream &operator<< (ostream &out, Rational &pFractB)
{
	if(pFractB.denominator == 1)
		out << pFractB.numerator << endl;
	else
		out << pFractB.numerator << "/" << pFractB.denominator << endl;
	
	return out;
}


//Addition operator function definition
Rational Rational::operator+ (Rational pFractB)
{
	
	Rational tObj;
	
	//calculates denominator 
	tObj.numerator = (denominator * pFractB.numerator) + (numerator * pFractB.denominator);
	
	//calculates numerator
	tObj.denominator = (denominator * pFractB.denominator);
	
	tObj.reduce();
	
	return tObj;
	
}

//Subtraction operator function definition
Rational Rational::operator- (Rational pFractB)
{
	
	Rational tObj;
	
	//calculates denominator
	tObj.numerator = (denominator * pFractB.numerator) - (numerator * pFractB.denominator);

	//calculates numerator
	tObj.denominator = (denominator * pFractB.denominator);
	
	tObj.reduce();

	return tObj;
}

//Multiplication operator function definition
Rational Rational::operator* (Rational pFractB)
{
	Rational tObj;
	
	//calculates the numerator
	tObj.numerator = numerator * pFractB.numerator;
	
	//calculates the denominator
	tObj.denominator = denominator * pFractB.denominator;
	
	tObj.reduce();
	
	return tObj;
}

//Division operator function definition
Rational Rational::operator/ (Rational pFractB)
{
	Rational tObj;
	
	//calculates the numerator
	tObj.numerator = numerator * pFractB.denominator;

	//calculates the denominator	
	tObj.denominator = denominator * pFractB.numerator;
	
	tObj.reduce();
	
	return tObj;
}

//Greater Than operator function definition
bool Rational::operator> (Rational &pFractB)
{
	bool greaterThan = 0;
	float tObj;
	float testObj;

	testObj = numerator / denominator;
	
	tObj = pFractB.numerator / pFractB.denominator;
	
	if(testObj > tObj)
		greaterThan = 1;
		
	return greaterThan;
}

//Less Than operator function definition
bool Rational::operator< (Rational &pFractB)
{
	bool lessThan = 0;
	float tObj;
	float testObj;
	testObj = numerator / denominator;
	
	tObj = pFractB.numerator / pFractB.denominator;
	
	if(testObj < tObj)
		lessThan = 1;
		
	return lessThan;
}

This is the client file:

Code:

#include<iostream>
#include"rational.h"
#include<fstream>

using namespace std;

ofstream outfile;
ifstream infile;


int main()
{
	Rational FractA, FractB, FractR;

	infile.open("ratdata.dat");
	outfile.open("ratout.txt");
	
	int cnt = 0;
	char oper;

	infile >> FractA;
	while (FractA != 0)
	{	cnt++;
		infile >> oper;
		infile >> FractB;

		if(oper == '+')
			FractR =  FractA + FractB;

		else if(oper == '-')
			FractR =  FractA - FractB;

		else if(oper == '*')
			FractR =  FractA * FractB;

		else if(oper == '/')
			FractR =  FractA / FractB;


		outfile << cnt << ": ";
		outfile << FractA << "  " << oper 
				<< "  "  << FractB << " = " 
				<< FractR << endl << endl;
		outfile << cnt << ": ";
		if (FractA > FractB)
			outfile << FractA << " is greater than " << FractB << endl;
		else 
			outfile << FractA << " is NOT greater than " << FractB << endl;
		outfile << "--------------------------------------" << endl;
		infile >> FractA;

	} // while


	return 0;
} // main

and here is the header file:

Code:

 
#ifndef RATIONAL_H
#define RATIONAL_H

#include <iostream> 

using namespace std;

class Rational 
{
friend istream &operator>> (istream &in, Rational &pFractB);
friend ostream &operator<< (ostream &out, Rational &pFractB);

public:
   Rational( int = 1, int = 1 ); // default constructor
   bool operator!=( const int );
   
   Rational operator+ (Rational pFractB);
   Rational operator- (Rational pFractB);
   Rational operator* (Rational pFractB);
   Rational operator/ (Rational pFractB);
   bool operator> (Rational &pFractB);
   bool operator< (Rational &pFractB);
   
private:
   int numerator;
   int denominator;
   void reduce(  );
};

#endif

The program runs, it is just the answers are wrong and the greater and less than functions are not working. I tested to see if the addition was working and it was before going through the reduce function.
So I though the relationship between the two functions was off somehow.

Thanks everyone for your help. I don't have a debugger so things are just a little harder for me when it comes to doing that lol. Thanks for all the tips and suggestions.