Classes, Member Functions, and Fractions problem

[polawyz]

Hi my professor for an entry level C++ class recently assigned us a homework problem, but hasn't quite taught us how to approach this problem.

The problem asks us to create a working C++ program that has a class called Fractions that has two int data members called numerator and denominator. The class's default constructor should provide both data members with default values of 1 if no explicit user initialization is provided. The constructor must also prohibit a 0 denominator value. We also have to include member functions for displaying an object's data and mathematical functions capable of adding, subtracting, multiplying and dividing two Fractions objects. Then we have to write another member function that reduces the fractions to their lowest common terms (ie. 12 / 15 becomes 3 / 5 )

I'm having several problems with this. How do I provide user inputs into class data members? I'm currently just doing it in the main function. How do I write a member function that takes two class objects? Is this even possible?

Here's what I have so far. I'm not quite sure how to use the sum, diff, prod, and div functions with the Fractions class objects.

#include <iostream>
using namespace std;

class Fractions{
private:
	int num;
	int denom;
public:
	Fractions(int = 1, int = 1);
	int setNum(int);
	int setDenom(int);
	void setFraction(int, int);
	void displayData();
	void sum(int, int, int, int);
	void diff(int, int, int, int);
	void prod(int, int, int, int);
	void div(int, int, int, int);
	void gcd(int, int);
};

Fractions::Fractions(int a, int b){
	num = a;
	denom = b;
}

void Fractions::setFractions(int a, int b){
	num = a;
	denom = b;
}

int Fractions::setNum(int a){
	num = a;
	return num;
}

int Fractions::setDenom(int b){
	denom = b;
	return denom;
}

void Fractions::displayData(){
	cout << "Fraction: " << num << "/" << denom << endl;
}

void Fractions::sum(int a, int b, int c, int d){
	double sum;
	sum = ((a * d) + (c * b)) / (b * d); 
	cout << "Sum: " << sum << endl;
}

void Fractions::diff(int a, int b, int c, int d){
	double diff;
	diff = ((a * d) - (c * b)) / (b * d); 
	cout << "Difference: " << diff << endl;
}

void Fractions::prod(int a, int b, int c, int d){
	double prod;
	prod = (a * c) / (b * d)
	cout << "Product: " << prod << endl;
}

void Fractions::div(int a, int b, int c, int d){
	double div;
	div = (a * d) / (b * c)
	cout << "Division: " << div << endl;
}

int main(){
	Fractions a, b;
	int num1, num2, denom1, denom2;

	//user inputs num and denom values for two fractions
	//do-while statement checks if user entered a 0 for denom
	cout << "Please enter a numerator: " << endl;
	cin >> num1
	cout << "Please enter a denominator: " << endl;
	cin >> denom1
	do{
		cout << "You cannot have 0 in the denominator." << endl;
                cout << "Please enter a denominator: " << endl;
		cin >> denom1
	}
	while(denom1 = 0);
	cout << "Please enter another numerator: " << endl;
	cin >> num2
	cout << "Please enter another denominator: " << endl;
	cin >> denom2
	do{
		cout << "You cannot have 0 in the denominator." << endl;
                cout << "Please enter a denominator: " << endl;
		cin >> denom2
	}
	while(denom2 = 0);

	a.setFractions(num1, denom1);
	b.setFractions(num2, denom2);
	a.displayData();
	b.displayData();

}

Any input would be great. Thanks a lot!

[caut_baia]

#include <iostream>
#include <iomanip>

using namespace std;

template <typename C> class fraction
  {
    protected:
      C numerator;
      C denominator;

    public:
      fraction() {}
      ~fraction() {}

      explicit fraction (C num,C denom) : numerator(num),denominator(denom)
        {
          frac(numerator,denominator);
        }
      C frac(C,C);
   };

template <typename C> C fraction<C> :: frac(C n,C d)
  {
    return n/d;
  }

int main ()
  {    
    fraction<float> a;
    fraction<float> b;
    float x,y,z,q;

    while (cin >> x >> y >> z >> q)         
    cout << setprecision(3) << a.frac(x,y) + b.frac(z,q);
  }