Thread: what am i doing wrong with inheritance?

Code:

#include <iostream>
using namespace std;

class Fraction
{
	protected:
		int num;
		int denom;
	public:
		Fraction() : num(1), denom (1)
		{  }
		Fraction(int top, int bottom): num(top), denom(bottom)
		{
			//check for divide by zero error
			if (denom == 0)
			{
				cout << "Divide by zero error, setting denominator equal to 1" << endl;
				denom = 1;
			}
		}
		int reduce(int p, int q)
		{
			int r;
			return ((r=p%q)==0)? q:reduce(q,r);
		}
		void showdata()
		{
			int gcd;
			gcd = reduce(num,denom);

			num /= gcd;
			denom /= gcd;
			if (num != 0)
				cout << num << "/" << denom << endl;

		}
		
		// overloaded addition
		Fraction operator + (Fraction)const;

		//overloaded minus
		Fraction operator - (Fraction f2) const;

	
		//overloaded multiplication
		Fraction operator * (Fraction f2) const;

	
		//overloaded division
		Fraction operator / (Fraction f2) const;

};

class Mixed : public Fraction
{
	private:
		int whole;
	public:
		Mixed(int w, int t, int b): whole(w), Fraction(t, b)


}; 


// Actual overloaded fraction definitions
Fraction Fraction::operator + (Fraction f2) const
	{
		int numtemp, denomtemp;
		//Fraction temp;
		numtemp = (num*f2.denom) + (denom * f2.num);
		denomtemp = (denom * f2.denom);
		return Fraction(numtemp, denomtemp);
	}

Fraction Fraction :: operator - (Fraction f2) const
	{
		int numtemp, denomtemp;
			numtemp = (num*f2.denom) - (denom * f2.num);
		denomtemp = (denom * f2.denom);
		return Fraction(numtemp, denomtemp);
	}

Fraction Fraction :: operator * (Fraction f2) const
	{
		int numtemp, denomtemp;
		numtemp = (num * f2.num);
		denomtemp = (denom * f2.denom);
		return Fraction(numtemp, denomtemp);
	}

Fraction Fraction :: operator / (Fraction f2) const
	{
		int numtemp, denomtemp;
		numtemp = (num * f2.denom);
		denomtemp = (denom * f2.num);
		return Fraction(numtemp, denomtemp);
	}



int main()
{
	
	
	//Fraction fract1, answer;
	//Fraction fract2 (1,0);
	Mixed m1(1,3,4);

	//answer = fract1 + fract2;
	//m1.showwhole(); answer.showdata();
	//answer = fract1 - fract2;
	//answer.showdata();
	//answer = fract1 * fract2;
	//answer.showdata();
	//answer = fract1 / fract2;
	//answer.showdata();
	return 0;		
}

without the inheritance mixed.. EVREYTHING works perfectly.. even witht he interited class without the public part, it compiles with no problem. its only when i add the public part im getting a problem. does it have to do with the constructor?
can u have a constructor in an inherited class?

im stupid
i realized i didnt have the brackets after the constructor

Originally posted by Stoned_Coder
The problem is operator +. You will need to provide an operator + for the mixed class that tells it how to add mixed objects together.
You have also broken a golden rule of c++. that rule is Never inherit from a concrete class. And this is why.....

Is a Mixed really a Fraction?

Answer that with yes it is or no it has a fraction.

If you answer has a, then how do you model that relationship in c++.

1. i havent done any of the overloaded operators for the mixed class yet.. i was just testing inheritance.

2. well, it wouldnt have been my first choice to do that, but its a requirement of the test... that a mixed number is a inherited class from fraction.

"well, it wouldnt have been my first choice to do that, but its a requirement of the test... that a mixed number is a inherited class from fraction."

So, you're cheating on a test?

how exactly was i cheating?

it was a take home test...