定义点Point类作为基类，在此基础上派生出直线Line类和圆Circle类，在Circle类的基础上以不同的属性派生出圆柱Cylinder类和球Spheroid。并要求基类和各派生类具有以下特点：

（1）　　Line类含有计算直线长度和斜率的成员函数。

（2）　　Circle类含有计算圆面积的成员函数。

（3）　　Cylinder类含有计算圆柱表面积和体积的成员函数。

（4）　　Spheroid类含有计算球体的表面积和体积的成员函数。

-Point definition of point type as the base category, on the basis of a straight line derived Circle Circle Line category and class, in the Circle class based on different attributes derived Cylinder class and ball cylinder Spheroid. And requested the base class, and factions of Health category has the following characteristics: (1) Line category contains the length and slope of a straight-line calculation of member functions. (2) Circle type of circular area containing the members of the calculation function. (3) Cylinder category contains cylindrical surface area and volume calculation of the member functions. (4) Spheroid Spheroid category contains the calculation of surface area and volume of the member functions.