#include Point &Point::operator--(void) { COMMONPOINT::x--; COMMONPOINT::y--; return *this; } Point Point::operator--(int /*prefixDummy*/) { Point prePoint(*this); --(*this); return prePoint; } Point Point::operator++(int /*prefixDummy*/) { Point prePoint(*this); ++(*this); return prePoint; } Point Point::operator+(const Point &somePoint)const { Point tmpPoint(*this); tmpPoint+=somePoint; return tmpPoint; }