Thread: overloading operator problems

this piece of code was fine when i replaced operator+-*/ with add, subtract, multiply, and divide. now i am getting errors that there are too many parameters in the overloading operators. i am not too familar with overloading operators. should i create a new class that contains all the parameters? a friend function (which i am also not too familar with)? also, is anybody familar with using the assert() method in the <cassert> library so the program will print out an error if a user inputs "0" as the denominator?

Code:

#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

///////////////////////////// fraction Class ///////////////////////////////
class fraction
{

private:
	int num;
	int denom;
	char dummychar;

public:


	fraction() : num(0), denom(0)
	{  }                                  // Constructor

	void getfraction()                    // Input fractions and sign
	{
		cout << "Please Enter Fraction: ";
	    cin >> num >> dummychar >> denom;
	    cout << "\n";
	}

	
	void operator+(fraction& fr1, fraction& fr2, fraction& fr3);  // decl. of addition function
	void operator-(fraction& fr1, fraction& fr2, fraction& fr3);  // decl. of subtract.function
	void operator*(fraction& fr1, fraction& fr2, fraction& fr3);  // decl. of multipl. function
	void operator/(fraction& fr1, fraction& fr2, fraction& fr3);    // decl. of division function
	void lowterms(fraction& fr3);               // declaration of lowterms function
		
	void showfraction(fraction& fr3)            // Display result on the screen
	{
		cout << "Answer= " << fr3.num << "/" 
			 << fr3.denom << "\n\n";
	}


};



// ------------------------------ Addition ------------------------------

void fraction::operator+(fraction& fr1, fraction& fr2, fraction& fr3)
{
	fr3.num = fr1.num*fr2.denom + fr1.denom*fr2.num;
	fr3.denom = fr1.denom*fr2.denom;
}

// ----------------------------- Subtraction-----------------------------

void fraction::operator-(fraction& fr1, fraction& fr2, fraction& fr3)
{
	fr3.num = fr1.num*fr2.denom - fr1.denom*fr2.num;
	fr3.denom = fr1.denom*fr2.denom;
}

// ---------------------------- Multiplication---------------------------

void fraction::operator*(fraction& fr1, fraction& fr2, fraction& fr3)
{
	fr3.num = fr1.num*fr2.num;
	fr3.denom = fr1.denom*fr2.denom;
}

// ------------------------------ Division ------------------------------

void fraction::operator/(fraction& fr1, fraction& fr2, fraction& fr3)
{
	fr3.num = fr1.num*fr2.denom;
	fr3.denom = fr1.denom*fr2.num;
}

// ------------------------ Lowest Term Function ------------------------

void fraction::lowterms(fraction& fr3)                  // Simplify to lowest terms
		{
			long tnum, tden, temp, gcd;

			tnum = labs(fr3.num);
			tden = labs(fr3.denom);
			
			if(tden==0)
			{ cout << "Illegal fraction: division by 0 \n"; exit(1); }
			else if(tnum==0)
			{ fr3.num=0; fr3.denom=1; return; }

			while(tnum != 0)
			{
				if(tnum < tden)
				{ temp=tnum; tnum=tden; tden=temp; }
			tnum = tnum - tden;
			}
		gcd = tden;
		fr3.num = fr3.num / gcd;
		fr3.denom = fr3.denom / gcd;

		}

char getsign();                        // declaration of getsign function

//////////////////////////////////////////////////////////////////////////

int main()
{
	fraction fract1, fract2, fract3;
	char response;
	char sgn;



	while (response != 'N')
	{

		fract1.getfraction();
		fract2.getfraction();
		sgn = getsign();
		

		switch (sgn)                   // Arithmetic Switch
		{
		case '+':
			fract3.operator+(fract1, fract2, fract3);
			break;
		case '-':
			fract3.operator-(fract1, fract2, fract3);               
			break;
		case '*':
			fract3.operator*(fract1, fract2, fract3);             
			break;
		case '/':
			fract3.operator/(fract1, fract2, fract3);                
			break;
		}

		fract3.lowterms(fract3);                   // function call to simplify terms

		fract3.showfraction(fract3);

		cout << "Calculate Another (Y or N)? ";
		cin >> response;
		cout << "\n\n";

	}

	return 0;
}

///////////////////////////////////////////////////////////////////////////////

char getsign()
	{
        char sign;

		cout << "Please Enter Mathematic Operation: ";
		cin >> sign;
		cout << "\n";
		return sign;
	}