CODEWITHSUNDEEP
c++classoverloadingoperator-keywordostream
user3437460
user3437460

Reputation: 17454

Overloading ostream << on one class and output data of another class

class Point2D
{
    protected:
            int x;
            int y;

    public:  
            Point2D () {x=0; y=0;}
            Point2D (int a, int b) {x=a; y=b;}        
            void setX (int);
            void setY (int);
            int getX ();
            int getY ();
};

class Line2D
{
    friend ostream& operator<< (ostream&, const Line2D&);
    private:
            Point2D pt1;
            Point2D pt2;
            double length;                                  
    public: 
            Line2D () {pt1 = Point2D(); pt2 = Point2D();}
            Line2D (Point2D ptA, Point2D ptB) {pt1=ptA; pt2=ptB;}     

            void setPt1 (Point2D);
            void setPt2 (Point2D);
            Point2D getPt1 ();
            Point2D getPt2 ();                
};
ostream& operator<< (ostream &out, const Line2D &l)
{
    //out << l.length << endl;    //Reading length works perfectly
    out << l.getPt1().getX() << endl;   //But how to read x from pt1 ?
    return out;
}

When I run these codes, I get error saying:

no matching function for call to Line2D::getPt1() const and

note: candidates are: Point2D Line2D::getPt1() <near match>.

If I am only trying to display length by overloading << operator , it works perfectly. But when I try to printx and y of Class::Point2D, I get error.

So what should be the proper way to print out x and y ?

Upvotes: 0

Views: 105

Answers (1)

juanchopanza
juanchopanza

Reputation: 227418

Your operator (rightly) takes a const reference. So any methods called via that reference must be const. For example,

Point2D getPt1 () const;
                  ^^^^^

You should also make the Point2D class getters const.

Upvotes: 4

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