编写C++程序完成以下功能：

（1）　　声明一个基类Shape（形状），其中包含一个方法来计算面积；

（2）　　从Shape派生两个类：矩形类和圆形类；

（3）　　从矩形类派生正方形类；

（4）　　分别实现派生类构造函数、析构函数和其他方法；

（5）　　创建派生类的对象，观察构造函数、析构函数调用次序；（提示及要求：1，可通过在构造与析构函数中加入输出提示信息的方式观察相关调用；可以使用system( pause )进行程序的暂停；2，能够理解并说明每一次构造与析构函数调用是哪个对象的调用，并观察和解释相关调用顺序及其原因）

对不同对象计算面积

-Write C++ program performs the following functions: (1) declare a base class Shape (shape), which contains a method to calculate the area　(2) Shape derived　two classes: Class rectangles and circles class　(3)　the rectangle class squares derived class　(4) respectively, to achieve a derived class constructors, destructors, and other methods　(5) create a derived class object, observe the constructor, destructor calls the order　(tips and requirements: 1, can be obtained by Construction and destructor added way to observe the output message related calls　you can use system (" pause" ) to pause the program　2, able to understand and explain every structure and destructor calls are calls which objects and observation and interpretation of the relevant sequence of calls and their causes) to calculate the area for different objects