本程序分为三个相对独立的部分，第一个部分是类clock的定义，第二个部分是时钟类成

员函数的具体实现，第三个部分是主函数mdn()。从前面的分析可以看到，声明了类及成员

函数只是对问题进行了抽象和封装的描述，问题的解决还要通过“类的实例”——对象之间的

消息传递来完成，这里的主程序的功能就是声明对象并传递消息。

程序中语句”yCtdk．showTime()就是对象调用函数的标准形式，它访问了类mYClMk

的成员函数5h。wTlme()。

-the procedures are divided into three relatively independent parts, a part of the definition of categories of clock, the second part of the clock function of the class members to achieve specific, the third part of the main function 4 (). From the previous analysis, we can see that kind of statement and the member function only on issues of the abstract and descr iption of the package, the solution through the "examples" -- between the target to complete messaging, the main program here is a statement of functional objects and impart information. Proceedings words "yCtdk.showTime () function is called the Object standard form, it visited members of the Class mYClMk function 5h. WTlme ().