if the Prototype is
andFunction declearation isCode:Point operator-=(const Point);
then I can Use it in this wayCode:Point Point::operator-=(const Point pt){ this->x -= pt.x; this->y -= pt.y; return *this; }
-----------------Code:*pt2 -= *pt1;
But whenandFunction declearation isCode:Point operator-=(const Point&);
then ALSO I can use it in this wayCode:Point Point::operator-=(const Point& pt){ this->x -= pt.x; this->y -= pt.y; return *this; }WHY ??Code:*pt2 -= *pt1;
Isnt there any difference between that Point& ??