一个复数类的实现方法，虽然简单，但对于初学者对于ｍｆｃ编程很有指导意义，这也是本人初学ｍｆｃ的时候第一个实列。-kind of a complex method, though simple, but for beginners for very mfc programming guide, This is my time learning mfc is an out clause.