trouble with overloaded operator

This is a discussion on trouble with overloaded operator within the C++ Programming forums, part of the General Programming Boards category; Hey I am having some trouble getting operator/ to overload to a midpoint formula for a Point class. And yes, ...

  1. #1
    Registered User
    Join Date
    Sep 2003
    Posts
    6

    trouble with overloaded operator

    Hey I am having some trouble getting operator/ to overload to a midpoint formula for a Point class. And yes, I have to make operator/ find the midpoint it was part of the assignment.

    Anyway I came up with this:

    Code:
    // Overloaded operator/ to return the midpoint
    // between two Point objects, however it does not
    // work and only returns garbage.
    
    Point & Point::operator/(const Point & p) const
    {
        return Point(((x + p.x) / 2.0), ((y + p.y) / 2.0));
    }
    here is the header file if you want to look at that too:

    Code:
    #ifndef POINT_CLASS_HEADER_INCLUDED
    #define POINT_CLASS_HEADER_INCLUDED
    
    #include <iostream>
    
    // A 2D point class
    class Point
    {
        double x, // x coordinate of point
               y; // y coordinate of point
    
    public:
        
        Point(void);
        Point(double new_x, double new_y);
        Point(const Point & p);
    
        void Output(void);   // output this point
        void Input(void);    // input this point
        double distance(Point other);   // distance between this point and other
    
        double get_x(void) { return x; }
        double get_y(void) { return y; }
    
        void set_x(double new_x);
        void set_y(double new_y);
    
        Point flip_x(void);
        Point flip_y(void);
    
        Point shift_x(double move_by);
        Point shift_y(double move_by);
    
        Point & operator=(const Point & p);
    
        Point & operator/(const Point & p) const;
        double operator-(const Point & p) const;
    
        bool operator==(const Point & p) const;
        bool operator!=(const Point & p) const;
    
        double operator[](const char axis) const;
        double & operator[](const char axis);
    
        friend std::istream & operator>>(std::istream & in, Point & p);
        friend std::ostream & operator<<(std::ostream & out, const Point & p);
    
    };
    
    #endif
    Anyway I was wondering if that is an invalid operator overload and if it is how can a hack it together to get it to work? Any ideas?

  2. #2
    Registered User jlou's Avatar
    Join Date
    Jul 2003
    Posts
    1,088

    Re: trouble with overloaded operator

    Originally posted by kkurz
    Hey I am having some trouble getting operator/ to overload to a midpoint formula for a Point class. And yes, I have to make operator/ find the midpoint it was part of the assignment.

    Anyway I came up with this:
    Code:
    // Overloaded operator/ to return the midpoint
    // between two Point objects, however it does not
    // work and only returns garbage.
    
    Point & Point::operator/(const Point & p) const
    {
        return Point(((x + p.x) / 2.0), ((y + p.y) / 2.0));
    }
    You are returning a reference to a new Point object created on the stack inside the operator/ function. When the function ends, all objects created inside it are destroyed, including the one that you returned a reference to. The reference you returned is then pointing at diddly poo. In this case I'd say return a Point and not a Point reference.

  3. #3
    Registered User
    Join Date
    Sep 2003
    Posts
    6

    Thanks so much

    Thanks, I really appreciate it that fixed everything right up.

    I really have to work on being able to go through my code and actually analyzing it, instead of reading it and saying, "sure that looks good to me."

    Thanks again.

    Kevin

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