EC++ Item 21: Don't try to return a reference when you must return an object

// Coded with Dev-C++ IDE
// When you use a static variable in the case...

#include <iostream>
using namespace std;


class Glass {
public:
    Glass() { cout<< "ctor.." << endl; }
    Glass(int x, int y)
    {
        cout<< "ctor.." << endl;
        this->x = x;
        this->y = y;       
    }
    friend Glass& operator+(const Glass& lhs, const Glass& rhs);
    friend bool operator==(const Glass& lhs, const Glass& rhs);
   
    int x;
    int y;
       
};


Glass& operator+(const Glass& lhs, const Glass& rhs)
{
    static Glass g;
    g.x = lhs.x+rhs.x;
    g.y = lhs.y+rhs.y;
    cout << "g.x : " << g.x << ", g.y: " << g.y << endl;
   
    return g;
}


bool operator==(const Glass& lhs, const Glass& rhs)
{
    return lhs.x == rhs.x && lhs.y == rhs.y;
   
}



int main()
{
    Glass g1(1, 3);
    Glass g2(1, 4);
    Glass g3(2, 2);
    Glass g4(2, 2);
   
    if ((g1+g2) == (g3+g4)) {
        cout << "equal" << endl;
    } else
        cout << "not equal" << endl;
   
   
   
    system("pause");
    return 0;
}

ctor..
ctor..
ctor..
ctor..
ctor..
g.x : 4, g.y: 4
g.x : 2, g.y: 7
equal