定义一个包含两个纯虚函数的抽象类shape:
　　class shape
　　　{
　　　　 public:
　　　　　　 virtual float Area()=0;
　　　　　　 virtual void SetData(float,float=0)=0;
　　　 };
　　成员函数SetData用于设置几何图形的属性值。成员函数Area()用于求出几何图形的面积。由shape派生出四种几何图形，分别是：三角形、矩形、正方形和圆形。
其它图形的派生类请自行编写。派生类的类名和属性如下：
1）类名 triangle　　属性：三角形的一边长w和此边上的高h
2）类名 rectangle　 属性：矩形的长w和宽h
3）类名 square　　　属性：正方形边长s
4）类名 circle　　　属性：圆的半径r
要求利用虚函数实现多态，编写一个求几何图形面积的普通函数CaclArea(shape *),其参数为抽象类shape的指针
在主函数中定义四种几何图形的对象，调用CaclArea()求四种几何图形对象的面积之和。(The member function SetData is used to set the property values of the geometry. The member function Area () is used to calculate the area of a geometric figure. Four geometric shapes derived from shape are triangle, rectangle, square and circle.
Other graphics derived class, please write your own. The class name and properties of the derived class are as follows:
1) class triangle attribute: triangle side length W and the edge of the high
2) class name rectangle property: rectangle long w and wide H
3) class name square property: square side length s
4) the class name circle property: the radius of the circle R
Requires the use of virtual functions to achieve polymorphism, the preparation of a geometric surface area of the common function CaclArea (shape *), its parameters for the abstract class shape pointer
Define four geometry objects in the main function and call CaclArea () to find the sum of the area of the four geometry objects.)