Operator Overloading

C++ lets a class define what an existing operator (+, ==, <<, and others) means for its own type:

class Point {
public:
    int x, y;

    Point(int x, int y) : x(x), y(y) {}

    Point operator+(const Point &other) const {
        return Point(x + other.x, y + other.y);
    }
};

Point a(1, 2), b(3, 4);
Point c = a + b; // calls operator+ — c is (4, 6)

Overloading operator<< is how a class becomes printable directly with std::cout:

std::ostream &operator<<(std::ostream &os, const Point &p) {
    os << "(" << p.x << ", " << p.y << ")";
    return os;
}

std::cout << c << std::endl; // (4, 6)

Common mistakes

• Overloading an operator to do something that surprises a reader (e.g. + that doesn't behave anything like addition) — overload only when the operator's usual meaning genuinely fits.