this

Hidden Pointer: this (1)

class point
{
public:
    void move(int x, int y)
    {
        _x += x;
        _y += y;
    }
private:
    int _x;
    int _y;
};

• Where’s the object?

• What’s the object?

• Where’s the member _x?

Hidden Pointer: this (2)

How would this be done in C?

C++	C
point p(5, 6); p.move(2, 3); First parameter of each method: this Method name is: move in class point	struct point p = {5, 6}; point_move(&p /*this*/, 2, 3); C has no “bound” methods Just plain functions

A-ha!!

• p.move(2, 3) is equivalent to point::move(&p, 2, 3)

• Just like C

Explicit this Pointer

For example to resolve ambiguity: say member are x and y (not prefixed with _)

class point
{
public:
    void move(int x, int y)
    {
        this->x += x;
        this->y += y;
    }
private:
    int x;
    int y;
};