頭文件中的
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
是什麼意思?
MSDN上原文:
>>_MSC_VER
>>Defines the compiler version. Defined as 1200 for Microsoft Visual C++ 6.0. >>Always defined.
>>_MFC_VER
>>Defines the MFC version. Defined as 0x0421 for Microsoft Foundation Class >>Library 4.21. Always defined.
>>#pragma once
>>Specifies that the file, in which the pragma resides, will be included (opened) >>only once by the compiler in a build. A common use for this pragma is the >>following:
>>//header.h
>>#pragma once
>>// Your C or C++ code would follow:
所以說_MSC_VER定義的是Microsoft Visual C++的版本而不是MFC的版本
#pragma once即爲樓上們的意思,建議不會的先看MSDN:)