建立一个point ( 点 )类，包含数据成员x,y ( 坐标点

class point { int x, y; public: point( int _x, int _y ) { x = _x; y = _y; } }; class circle : public point { int r; public: circle( int x, int y, int _r ) : point(x,y) { r = _r; } }; class cylinder : public circle { int h; public: