CODEWITHSUNDEEP
c++operator-overloading
user1825608
user1825608

Reputation:

Weird behaviour of overloaded + operator

I have made class which represents Line Linia (aX+bY=c) and I overloaded + operator so now it now returns new Linia object which has c = c + b/argument. But the problem is that when I use this operator all the fields of the given Line object become 0 

   #include <iostream>

using namespace std;
struct Q{
public:
double x,y;
    Q(double x, double y){
        this->x = x;
        this->y = y;
    }
     friend ostream& operator<< (ostream &wyjscie, Q const& ex){
        wyjscie<<"("<<ex.x<<","<<ex.y<<")";
        return wyjscie;
     }

};
class Linia{
public:
    double a,b,c;
    Linia (double a, double b, double c){
        this->a = a;
        this->b = b;
        this->c = c;
    }
    Linia operator+ (double i){
       return Linia(a, b, c + i/b);
    }
      Linia operator- (double i){
       return Linia(a, b, c - i/b);
    }
    Q operator* (const Linia& i){
        double w = a*i.b - b*i.a;
        double wx = -c*i.b + i.c*b;
        double wy = a*(-i.c) + i.c*c;
        double x = wx/w, y = wy/w;
        cout<<*this<<endl;
        cout<<i<<endl;
        return Q(x,y);
    }
     friend ostream& operator<< (ostream &wyjscie, Linia const& ex){
        wyjscie<<ex.a<<"x + "<<ex.b<<"y = "<<ex.c;
        return wyjscie;
    }

};//podwyzszenie przez ile/B

int main()
{
    Linia* pionowa = new Linia(0,1,0);
    Linia* l = new Linia(1,1,3);
 //   Q q = (*l) * (*pionowa);
    cout<<"linia przed podniesieniem "<<*l<<endl;
 //   cout<<"punkt przeciecia przed podniesieniem: "<<q<<endl;
    l = l+3;
    cout<<"Line highered"<<*l<<endl;
    l = l-3;
    cout<<"Line Lowered "<<*l<<endl;
//    q = (*l) * (*pionowa);
 //   cout<<"punkt przeciecia po podniesieniu: "<<q<<endl;
    cout << "Hello world!" << endl;
    return 0;
}

Upvotes: 1

Views: 84

Answers (1)

juanchopanza
juanchopanza

Reputation: 227418

You are doing pointer arithmetic here. That means that l ends up pointing to some address where is shouldn't:

Linia* l = new Linia(1,1,3);
l = l+3; // l is a pointer!!!

If you stop using new and raw pointers everywhere it might just work.

int main()
{
    Linia pionowa(0,1,0);
    Linia l(1,1,3);
    l = l+3;
    cout<<"Line highered"<< l <<endl;
    l = l-3;
    cout<<"Line Lowered "<< l <<endl;

}

Upvotes: 5

Related Questions