先建立一个点类Point，包含数据成员x，y（坐标点）。以它为基类，派生出圆类Circle，增加数据成员radius（半径），再以Cirlcle类为直接基类，派生出圆柱体类Cylinder，再增加数据成员height（高）。要求：

（1）每个类都有构造函数、用于从键盘获取数据的成员函数set()，用于显示数据的成员函数display()。

（2）用虚函数输出各类对象信息

-First establish a point class Point contains data members x, y (coordinate points). The base class for derived round class Circle, increased data member radius (radius), then Cirlcle class direct base class, the cylinder class derived Cylinder, additional data members height (H). Requirements: (1) for each class constructor, used to obtain data from the keyboard member function set () member function display (used to display data). (2) virtual function to output all kinds of object information