Im having a problem with classes Please help

[FizleYoWizle]

So I am writing a program that is supposed to produce a rational number (numerator/denominator) and the program works until I need to call .reduce() I am pretty sure that the problem is syntax or how I call int gCD inside of reduce() someone please help

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

class RationalNumber{
private:
	int numer;
	int denom;
	int gCD(int num1, int num2);
	void reduce();
public:
	RationalNumber(int num1, int num2);
	RationalNumber(int num1);
	RationalNumber add(RationalNumber& num);
	RationalNumber sub(RationalNumber num);
	RationalNumber mul(RationalNumber num);
	RationalNumber div(RationalNumber num);
	bool equals(RationalNumber num);
	bool  less_than(RationalNumber num);
	bool greater_than(RationalNumber num);
	RationalNumber input(istream& in);
	void output(ostream& out);
};
void RationalNumber::reduce()
{
	int r = 0, num1 = abs(numer), num2 = abs(denom);

	r = gCD(num1, num2);

	numer = numer / r;

	denom = denom / r;
}
int gCD(int num1, int num2)
{
	while (num1 != num2)
	{
		if (num1 > num2)
			num1 = num1 - num2;
		else
			num2 = num2 - num1;
	}

	return num1;
}
RationalNumber::RationalNumber(int num1, int num2)
{
	numer = num1;
	denom = num2;
}
RationalNumber::RationalNumber(int num1)
{
	numer = num1;
	denom = 1;
}
RationalNumber RationalNumber::add(RationalNumber& num)
{
	int num1 = 0, num2 = 0;
	int x = 0;
	x = num.denom;
	num1 = num.numer *denom;
	num2 = num.denom * denom;
	num1 += numer * x;
	RationalNumber added(num1, num2);

	return added;
}
RationalNumber RationalNumber::sub(RationalNumber num)
{
	int num1 = 0, num2 = 0;
	int x = 0, a = 0;

	x = num.denom;
	a = denom;
	numer = numer* x;
	denom = denom * x;
	num.numer = num.numer * a;
	num.denom = num.denom * a;
	num1 = numer - num.numer;
	num2 = x*a;

	RationalNumber subtracted(num1, num2);

	return subtracted;
}
RationalNumber RationalNumber::mul(RationalNumber num)
{
	int num1 = 0, num2 = 0;
	num1 = numer * num.numer;
	num2 = denom * num.denom;

	RationalNumber multiplied(num1, num2);

	return multiplied;
}
RationalNumber RationalNumber::div(RationalNumber num)
{
	int num1 = 0, num2 = 0;
	num1 = numer * num.denom;
	num2 = denom * num.numer;

	RationalNumber divided(num1, num2);

	return divided;
}
bool RationalNumber::equals(RationalNumber num)
{
	double a = 0, b = 0;
	a = numer / denom;
	b = num.numer / num.denom;
	if (a = b)
		return true;
	else
		return false;
}
bool  RationalNumber::less_than(RationalNumber num)
{
	double a = 0, b = 0;
	a = numer / denom;
	b = num.numer / num.denom;
	if (a < b)
		return true;
	else
		return false;
}
bool RationalNumber::greater_than(RationalNumber num)
{
	double a = 0, b = 0;
	a = numer / denom;
	b = num.numer / num.denom;
	if (a > b)
		return true;
	else
		return false;
}
RationalNumber RationalNumber::input(istream& in)
{
	cout << "For the Numerator: " << endl;
	in >> numer;
	cout << "and the Denomonator:" << endl;
	in >> denom;
	RationalNumber inputed(numer, denom);
	return inputed;
}
void RationalNumber::output(ostream& out)
{
	reduce();
	if (numer < 0 && denom < 0)
		out << numer *-1 << "/" << denom *-1 << endl;
	else if (numer > 0 && denom < 0)
		out << numer *-1 << "/" << denom *-1 << endl;
	else if (numer == 0)
		out << "Numer is zero, 0" << endl;
	else if (denom == 0)
		out << "Denom is zero, unavaliable" << endl;
	else
		out << numer << "/" << denom << endl;

}
int main()
{
	RationalNumber op1 = RationalNumber(1, -3);
	op1.output(cout);

	RationalNumber op2 = RationalNumber(2);
	op2.output(cout);

	RationalNumber op3 = RationalNumber(-2, -4);
	op3.output(cout);

	RationalNumber sum = op1.add(op2);
	cout << "sum op1 and 2 (5/3): ";
	sum.output(cout);


	RationalNumber difference = op2.sub(op3);
	cout << "difference op2 and 3 (3/2): ";
	difference.output(cout);

	RationalNumber product = op1.mul(op3);
	cout << "product op 1 3(-1/6): ";
	product.output(cout);

	RationalNumber quotient = op3.div(op2);
	cout << "quotient 3 and 2 1/4: ";
	quotient.output(cout);

	bool lessThan = op1.less_than(op2);
	bool greaterThan = op1.greater_than(op3);
	bool equalTo = op1.equals(RationalNumber(2, -6));
	bool equalTo2 = op1.equals(op2);

	cout << lessThan << endl;
	cout << greaterThan << endl;
	cout << equalTo << endl;
	cout << equalTo2 << endl;

}

[tpb]

You need to define gCD as part of RationalNumber:

int RationalNumber::gCD(int num1, int num2)
{
    // ...
}

And you should make it a static member of the class:

	static int gCD(int num1, int num2);

And in equals() you're using = where you mean ==.

[TheIdeasMan]

Hi,

The compiler is your friend:

In member function 'bool RationalNumber::equals(RationalNumber)':
111:11: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
/tmp/ccCcnZ3o.o:
In function `RationalNumber::reduce()':
:(.text+0x1d): undefined reference to `RationalNumber::gCD(int, int)'
collect2: error: ld returned 1 exit status

If a function doesn't use any of the class members then it doesn't need to be in the class, so move the gCD function outside the class declaration.


= is for assignment == is for equality test

There are compound assignment operators:

numer /= r; //same as numer = numer / r;

http://en.cppreference.com/w/cpp/language/operator_assignment

Other things to do:

Get rid of using namespace std; it will bite you in the ass one day - Google it.

Split the class declaration into a header file - I like to use *.hpp for C++ headers ; put the definition of the functions into a cpp file. Name these files the same as the class name.

[FizleYoWizle]

tpb you are an angel, I have been looking at the gCD function for so long just frustrated and then when it was the only syntax I did not know how to respond thank you, and TheIdeasMan, I am well aware of using namespace std; but for my computer science class my teacher told us not to get rid of it that we will start using new headers next year. Thanks for your help everyone.