MSVC:fix warning: _WIN32_WINNT not defined. Defaulting to _WIN32_WINNT_MAXVER (see WinSDKVer.h)

末蓝、 2022-05-13 01:10 49阅读 0赞

编译一个从旧版本MSVC工程时没头没脑的报了个警告(我的编译器是Visual Studio 2015):

> \_WIN32\_WINNT not defined. Defaulting to \_WIN32\_WINNT\_MAXVER (see WinSDKVer.h)

意思就是没有定义`_WIN32_WINNT`，所以被缺省定义为`_WIN32_WINNT_MAXVER`。  
网上的解决方案都是一样的(参见这个CSDN博客：[《\_WIN32\_WINNT not defined. Defaulting to \_WIN32\_WINNT\_MAXVER (see WinSDKVer.h》][WIN32_WINNT not defined. Defaulting to _WIN32_WINNT_MAXVER _see WinSDKVer.h]

步骤1  
编译时加入`_WIN32_WINNT`定义  
步骤2  
代码中include `sdkddkver.h`,比如在`StdAfx.h`中添加`#include <sdkddkver.h>`

#ifndef WINVER
    #define WINVER 0x0502
    #endif
    
    #ifndef _WIN32_WINNT
    #define _WIN32_WINNT 0x0502
    #endif
    #include <sdkddkver.h>

有了解决方案，总要知道为什么  
为什么要加`_WIN32_WINNT`这个定义呢？  
添加这个定义用于显式指定程序运行的平台,比如 `_WIN32_WINNT=0x0502`就是指定程序运行的平台为Windows Server 2003 with SP1, Windows XP with SP2.(`0x0502`的定义来源参见本文最后的参考资料链接)  
新的VC版本(比如VS2015)不再支持过于旧的Windows平台(比如Windows 95, Windows 98, Windows ME, Windows NT or Windows 2000),如果你要的应用程序要求支持这些旧的平台，就要显式定义`_WIN32_WINNT`

如果不显式定义`_WIN32_WINNT`，只要include `sdkddkver.h`,在`sdkddkver.h`中会自动定义`_WIN32_WINNT`为当前MSVC定义的最高可用的windows平台(`_WIN32_WINNT_MAXVER` )。比如VS2015下会定义为`0x0603`(`_WIN32_WINNT_WINBLUE`)，那么程序就不能运行在低于这个版本的Window系统上。

> Visual C++ no longer supports targeting Windows 95, Windows 98, Windows ME, Windows NT or Windows 2000. If your WINVER or \_WIN32\_WINNT macros are assigned to one of these versions of Windows, you must modify the macros. When you upgrade a project that was created by using an earlier version of Visual C++, you may see compilation errors related to the WINVER or \_WIN32\_WINNT macros if they are assigned to a version of Windows that is no longer supported. @[https://msdn.microsoft.com/en-us/library/6sehtctf.aspx][https_msdn.microsoft.com_en-us_library_6sehtctf.aspx]

# 参考资料 #

[《Using the Windows Headers》][Using the Windows Headers]  
[《Modifying WINVER and \_WIN32\_WINNT》][https_msdn.microsoft.com_en-us_library_6sehtctf.aspx]  
[《’\_WIN32\_WINNT’ / ‘WINVER’ : macro redefinition》][WIN32_WINNT_ _ _WINVER_ _ macro redefinition]  
[《Setting a ‘compatibility’》][Setting a _compatibility]

[WIN32_WINNT not defined. Defaulting to _WIN32_WINNT_MAXVER _see WinSDKVer.h]: https://blog.csdn.net/xiaolongwang2010/article/details/7550505
[https_msdn.microsoft.com_en-us_library_6sehtctf.aspx]: https://msdn.microsoft.com/en-us/library/6sehtctf.aspx
[Using the Windows Headers]: https://docs.microsoft.com/zh-cn/windows/desktop/WinProg/using-the-windows-headers
[WIN32_WINNT_ _ _WINVER_ _ macro redefinition]: https://stackoverflow.com/questions/41376557/win32-winnt-winver-macro-redefinition
[Setting a _compatibility]: https://social.msdn.microsoft.com/Forums/en-US/11ad83d2-2ef3-4d14-8f03-b839bce44423/setting-a-compatibility?forum=vcmfcatl