一个程序计算三角，正方形和圆形的面积。

分析：依题意，可以抽象出一个基类CBase，在其中说明一个虚函数，用来求面积，并利用单接口、多实现版本设计各个图形求面积的方法。C++初学者的大作业

-A program to calculate the triangle, square and round the area. Analysis: According to the meaning of problems can be an abstract base class CBase, which shows a virtual function, used to find the area and use a single interface, multiple implementations of the design requirements of each area of ​ ​ graphical methods. C++ beginners big job