说明：  VC++动态链接库编程之基础慨念： Visual C++支持三种DLL，它们分别是Non-MFC DLL（非MFC动态库）、MFC Regular DLL（MFC规则DLL）、MFC Extension DLL（MFC扩展DLL）
(VC DLL programming basis for the conception : Visual C support three DLL, They are the Non-MFC DLL (Dynamic Library MFC), MFC Regular DLL (MFC rules DLL), MFC Extension DLL (MFC extension DLL))