说明：  在设计良好的面向对象系统中，为了压缩其对象内部的空间，仅留两个函数用于对象的拷贝：一般称为拷贝构造函数（copy constructor）和拷贝赋值运算符（copy assignment operator）。我们将它们统称为拷贝函数（copying functions）。如果需要，编译器会生成拷贝函数，而且阐明了编译器生成的版本正象你所期望的：它们拷贝被拷贝对象的全部数据。
(in a well-designed object-oriented systems, in order to reduce its target within the space, leaving only two function to copy the Object : General Constructors called copy (copy constructor) and copy assignment operator (copy assignment operator). We will copy them collectively function (copying functions). If necessary, the compiler will generate copy function, but also to clarify the compiler generated version Just as you expect : they copy the object being copied all the data.)