运算符重载以及利用纯虚函数实现多态性设计一个计算图形面积的类库-Operator overloading and the use of pure virtual functions to achieve polymorphism in the area to design a graphics library computing

讲述输入法编程和，C++的入门。比如，C++的类，继承性，多态性。还有一些编程小技巧。-About the input method programming, C++ the entry. For example, C++ classes, inheritance, and polymorphism. There are some programming tips.