2、　　编写一个程序计算出球、圆柱和圆锥的表面积和体积。

a)　　要求：

i.　　定义一个基类圆，至少含有一个数据成员半径；

ii.　　定义基类的派生类球、圆柱、圆锥，都含有求表面积和体积的成员函数和输出函数。

iii.　　定义主函数，求球、圆柱、圆锥的和体积。

-2, write a program to calculate the ball, cylindrical and conical surface area and volume. a) asked: i. defining a base class circle, has at least one data member radius　ii. the definition of base class of derived classes sphere, cylinder, cone, surface area and volume contain a member of demand functions and output functions. iii. defines the main function, find the ball, cylinder, cone and sizes.