Output is printing twice with overloaded operators

[TaytayB]

Hey there! I'm having an issue with output, luckily everything else works!!
I'm working with Mixed Numbers and operations on them.
So, here's the code I'm testing with:

int main()
{
	Mixed  m1(5), m2(1,1,1), m5(2,2,3);
cout << "m1+m2= " << m1+m2 << endl;
cout << "m1 + 10=" << m1+10 << endl;
cout << "m1 - 10=" << m1-10 << endl;
	return 0;
}

And here is the output for that code:

7/1

m1+m2= 7/1

15/1

m1 + 10= 15/1

-5/1

m1 - 10= -5/1

I don't know where the error is and I feel like I've checked everywhere, Can someone else review my code and please help me find it?

Here is my Header file:

/*=========================================================->
File name: fract.h
	This file contains all the fract class information
	for project 3 in COP3330 taught by Dr. David Gaitros.

Written by: Taylor Jay Brockhoeft
Last edit date: 2/16/13
<-=========================================================*/
#ifndef fract_H
#define fract_H

#include <iostream>
using namespace std; 

const int DEFAULT_VAL = 0;

class fract
{
	friend ostream &operator<<(ostream &out, fract a);
	friend istream &operator>>(istream &in, fract &c);
	friend fract operator/ (const fract &fract1,  const fract &fract2);
	friend fract operator* (const fract &fract1,  const fract &fract2);
	friend fract operator+ (const fract &fract1,  const fract &fract2);
	friend fract operator- (const fract &fract1,  const fract &fract2);
	friend bool operator== (const fract &fract1,  const fract &fract2);
	friend bool operator!= (const fract &fract1,  const fract &fract2);
	friend bool operator< (const fract &fract1,  const fract &fract2);
	friend bool operator> (const fract &fract1,  const fract &fract2);
	friend bool operator<= (const fract &fract1,  const fract &fract2);
	friend bool operator>= (const fract &fract1,  const fract &fract2);

public:
	fract(const int i=0);
	fract(const int i, const int n, const int d);
	double Evaluate();
	void ToFraction();
	void Simplify();
	int gcd(int, int);
	fract& operator++ ();
	fract operator++ (int);
	fract& operator-- ();
	fract operator-- (int);

private:
	int integer;
	int numerator; 
	int denominator;
	char slash;//For input of slash
};
#endif 

Again, an extra pair of eyes and review would be super appreciated!!!

[TaytayB]

#include "fract.h"
fract::fract(const int i)
{
	integer = i;
	numerator = 0;
	denominator = 1;
}
fract::fract(const int i, const int n, const int d)
{
	integer = i;
	numerator = n;
	denominator = d;
}
ostream &operator<<(ostream &out, fract a)     
{
	cout << ' ';//Prints leading whitespace
	if(((a.integer<0)^(a.numerator<0))&&(a.denominator<0))
	{
		a.integer = abs(a.integer);
		a.numerator = abs(a.numerator);
		a.denominator = abs(a.denominator);
	}
	if((a.integer<0)&&(a.numerator<0))
		a.integer = -1*a.integer;
	if((a.integer != 0))
		out<<a.integer<<' ';
	if(a.numerator != 0)
	{
		out<<a.numerator<<'/'<<a.denominator;
	}
	if((a.integer == 0)&&(a.numerator == 0)&&(a.denominator == 0))
	{
		out << DEFAULT_VAL << endl;
	}
	cout << endl;//Prints newline

	return out;
}
istream &operator>>(istream &in, fract &c)
{
	cout << "Please enter an Integer and a fraction as \"I N/D\": " << endl;
	in >> c.integer;
	in >> c.numerator;
	in >> c.slash;
	in >> c.denominator;
	if(((c.integer < 0)&&(c.numerator < 0))||(c.denominator<=0))
	{
		c.integer = 0;
		c.numerator = 0;
		c.denominator = 0;
	}
	if((c.integer>0)&&(c.numerator<0))
	{
		c.integer = c.integer*-1;
		c.numerator = abs(c.numerator);
		c.denominator = abs(c.denominator);
	}
	return in;
}
double fract::Evaluate()//Not all paths return a value Warning error C4715 on 2/15/13
{
	bool isNegative = false;
	double fraction = (double)numerator/(double)denominator;
	if((numerator==0)&&(denominator==0))
		return integer;
	if(integer < 0)
	{
		abs(integer);
		isNegative = true;
	}
	if(isNegative == false)
		return integer+fraction;
	else if(isNegative == true)
		return (integer-fraction);
}
void fract::ToFraction()
{
		if(integer<0)
			numerator = (integer*denominator) - numerator;
		else
			numerator = (integer*denominator) + numerator;
		integer = 0;
}
void fract::Simplify()
{
	int greatestCommonDenominator = gcd(numerator,denominator);

	if(greatestCommonDenominator==0)
		cout << integer << endl;
	else if((denominator/greatestCommonDenominator != 0)&&(numerator/greatestCommonDenominator != 0))
	{	
		numerator=numerator/greatestCommonDenominator;
		denominator=denominator/greatestCommonDenominator;
		if(integer != 0)
			cout << integer << ' ';
		cout << numerator << "/" << denominator << endl << endl;
	}
	else
		cout << 0;
}
int fract::gcd(int a, int b)
{
	if(b == 0)
		return a;
	else
		return gcd(b, a%b);
}
bool operator== (const fract &fract1,  const fract &fract2)
{
	fract a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	a.Simplify();
	b.Simplify();
	if((a.numerator == b.numerator)&&(a.denominator == b.denominator))
				return true;
	else
		return false;
}
bool operator!= (const fract &fract1,  const fract &fract2)
{
	fract a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	a.Simplify();
	b.Simplify();
	if((a.numerator != b.numerator)||(a.denominator != b.denominator))
		return true;
	else
		return false;
}
bool operator> (const fract &fract1,  const fract &fract2)
{
	fract a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	a.Simplify();
	b.Simplify();
	if((a.numerator*b.denominator) > (b.numerator*a.denominator))
		return true;
	else
		return false;
}
bool operator< (const fract &fract1,  const fract &fract2)
{
	fract a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	a.Simplify();
	b.Simplify();
	if((a.numerator*b.denominator) < (b.numerator*a.denominator))
		return true;
	else
		return false;
}
bool operator>= (const fract &fract1,  const fract &fract2)
{
	fract a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	a.Simplify();
	b.Simplify();
	if((a.numerator*b.denominator) >= (b.numerator*a.denominator))
		return true;
	else
		return false;
}
bool operator<= (const fract &fract1,  const fract &fract2)
{
	fract a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	a.Simplify();
	b.Simplify();
	if((a.numerator*b.denominator) <= (b.numerator*a.denominator))
		return true;
	else
		return false;
}
fract operator/ (const fract &fract1,  const fract &fract2)
{
	fract fraction, a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	
	fraction.numerator = (a.numerator * b.denominator);
	fraction.denominator = (b.numerator * a.denominator);

	fraction.Simplify();
	return fraction;

}
fract operator* (const fract &fract1,  const fract &fract2)
{
	fract fraction, a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	
	fraction.numerator = (a.numerator * b.numerator);
	fraction.denominator = (a.denominator * b.denominator);

	fraction.Simplify();
	return fraction;

}
fract operator+ (const fract &fract1,  const fract &fract2)
{
	fract fraction, a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();

	fraction.numerator = (a.numerator * b.denominator) + (b.numerator * a.denominator);
	fraction.denominator = (a.denominator * b.denominator);
	
	fraction.Simplify();

	return fraction;

}
fract operator- (const fract &fract1,  const fract &fract2)
{
	fract fraction, a,b;
	a = fract1;
	b = fract2;
	a.ToFraction();
	b.ToFraction();
	
	fraction.numerator = (a.numerator * b.denominator) - (b.numerator * a.denominator);
	fraction.denominator = (a.denominator * b.denominator);

	fraction.Simplify();
	return fraction;

}
fract& fract::operator++ () 
{
	integer++;
	return *this;
}
fract fract::operator++ (int ignorethis)
{
	fract temp = *this;
	++integer;
	return temp;
}
fract& fract::operator-- ()
{
	integer--;
	return *this;
}
fract fract::operator-- (int ignorethis)
{
	fract temp = *this;
	--integer;
	return temp;
}

[ne555]

For a really weird reason, there are output statements in `Simplify()'