纯虚函数与抽家类 Shape →抽象类 Int x,y drawL; //KlE 纯虚函数 area( //AE setvalued Square Circle drawL drawL a0: area areao纯虚函数与抽象类 抽象类 纯虚函数 Square draw(); area(); Circle draw(); area(); Shape draw();//虚 area();//虚 setvalue(); int x,y;