1、　　矩形

编写C++程序完成以下功能：

（1）　　定义一个Point类，其属性包括点的坐标，提供计算两点之间距离的方法；

（2）　　定义一个矩形类，其属性包括左上角和右下角两个点，提供计算面积的方法；

（3）　　创建一个矩形对象，提示用户输入矩形左上角和右下角的坐标；

（4）　　观察矩形对象以及Point类成员的构造函数与析构函数的调用；

（5）　　计算其面积，并输出

-1, rectangular prepared C++ Process is complete the following functions: (1) the definition of a Point, whose properties include the coordinates of points to provide the calculation method of distance between two points　(2) the definition of a rectangle, whose properties include the left angle and the bottom right corner of the two points, to provide the calculation method of the area　(3) to create a rectangular object, prompts the user to enter the upper left corner and the lower right corner of rectangular coordinates　(4) Observation Point Class of rectangular object, as well as members of constructor and destructor function call　(5) to calculate their size, and output