动态束定与虚函数.

当一个类是从一个或多个类派生出来时，往往会出现

多个函数名相同且参数个数和参数类型也完全相同的

成员函数，分别实现不同的功能。-Dynamic beam set with virtual function.

When a class is derived from one or more classes, often appear

More function names are the same and the number of parameters and parameter types are also exactly the same

The member function, respectively, to achieve different functions.