C++ type qualifier problem


As part of my Computer Software Development degree, one of my labs consists of creating a calculator class template and a fraction class.

The problem is with my fraction class. My task is now to overload the plus operator to allow two fractions to be added together.


#include "Fraction.h"

const Fraction Fraction::operator+ (const Fraction &rhs) const
    return Fraction(_num * rhs.GetDen() + (rhs.GetNum() * _den), _den * rhs.GetDen());


#pragma once

class Fraction
        Fraction(const int &num, const int &den) : _num(num), _den(den) {}
        ~Fraction(void) {}
        const int GetNum(void) { return _num; }
        const int GetDen(void) { return _den; }
        const Fraction operator+ (const Fraction &rhs) const;

        const int _num, _den;

Visual Studio complains that my fraction accessors cannot 'convert this pointer from const fraction to fraction &'. I'm completely baffled.

Best Solution

You need to qualify your accessors as const too:

int GetNum(void) const { return _num; }

BTW, qualifying the return type as const int does not really make sense, it will be an int anyway. Your compiler should emit a warning.