说明：  其实这个程序也很简单，但是我觉得它对于刚学c++的人来说比较有用处，因为它可以帮助你更加深刻的理解面向对象程序设计的真谛
(In fact, the procedure is simple, but I think it has just learning to c for people who use more, because it can help you to a more profound understanding of object-oriented programming design of the essence)