声明一个圆类作为基类，含成员数据半径R；有成员函数：构造函数实现对基类成员数 据的初始化、计算圆面积的成员函数、输出的成员函数，要求输出圆半径R。把圆类作为基 类，通过公有继承，派生圆柱体类，派生类新增成员数据有高（H）；新增成员函数有构造函 数、计算圆柱体体积的函数、输出所有成员的函数。main()完成派生类对象的定义和相关函 数的测试-Declare a class as a base class circle, including members of the data radius R　have member functions: a constructor to initialize the base class members realize the data, calculate the area of ​ ​ a circle member function, the output member functions required output radius R. The round class as a base class, through public inheritance, derived cylinder class, the derived class member data new high (H)　new member functions have a constructor, to calculate the volume of a cylinder function, the output function of all members. main () test to complete the derived class object definitions and related functions