How to get rid of _WIN32_WINNT not defined warning?

Question

_WIN32_WINNT not defined. Defaulting to _WIN32_WINNT_MAXVER (see WinSDKVer.h)

This error keeps popping up during my compilation. It doesn't seem to affect compilation, but how should I get rid of it? Am I risking anything by ignoring it?

Answer 1

Set it to the oldest Windows Operating System you want your program to run on. The possible values are given in this MSDN article, Using the Windows Headers.

You can define these symbols by using the #define statement in each source file, or by specifying the /D compiler option supported by Visual C++.

For example, to set WINVER in your source file, use the following statement:

 #define WINVER 0x0502    // Windows Server 2003 with SP1, Windows XP with SP2 

To set _WIN32_WINNT in your source file, use the following statement:

#define _WIN32_WINNT 0x0502    // Windows Server 2003 with SP1, Windows XP with SP2 

To set _WIN32_WINNT using the /D compiler option, use the following command:

cl -c /D_WIN32_WINNT=0x0502 source.cpp 

Answer 2

It is defined for you through WinSDKVer.h. So just define it explicitly on the top of your source code (e.g. in the beginning of stdafx.h) and you will get rid of the warning.

Having it defined to the same value (as compared to _WIN32_WINNT_MAXVER from WinSDKVer.h) is highly unlikely to break anything.

For example, WinSDKVer.h of Windows® Software Development Kit (SDK) for Windows 7 and .NET Framework 3.5 Service Pack 1 contains:

// This list contains the highest version constants supported by content 
// in the Windows SDK.

// [...]
#define _WIN32_WINNT_MAXVER     0x0601

Answer 3

Solving in VS2019

Ways to solve this and a link to possible values to use can be found here in the super answer by user93353 which I used to solve the problem.

https://stackoverflow.com/a/12871547/3070485

However, after reading the solution, I set my compiler option in my IDE which is Visual Studio 2019.

For anyone wanting to set it there quickly and wanting to know the location (as these things change from IDE release to release, or maybe someone is more familiar with another IDE), here is where it went.

Configuration Properties
C/C++
Preprocessor
Preprocessor Definitions
_WIN32_WINNT=0x0502