C++ – msbuild: set a specific preprocessor #define in the command line

c++msbuildvisual-studio

In a C++ file, I have a code like this:

#if ACTIVATE
#   pragma message( "Activated" )
#else
#   pragma message( "Not Activated")
#endif

I want to set this ACTIVE define to 1 with the msbuild command line.

It tried this but it doesn't work:

msbuild /p:DefineConstants="ACTIVATE=1"

Any idea?

Best Solution

I'm a little late to the party (only 4 years or so), but I just had to workaround this problem on a project, and stumbled across this question while searching for a fix. Our solution was to use an environment variable with /D defines in it, combined with the Additional Options box in visual studio.

  1. In Visual Studio, add an environment variable macro, $(ExternalCompilerOptions), to the Additional Options under project options->C/C++->Command Line (remember both Debug and Release configs)
  2. Set the environment variable prior to calling msbuild. Use the /D compiler option to define your macros
    c:\> set ExternalCompilerOptions=/DFOO /DBAR 
    c:\> msbuild

Item #1 ends up looking like this in the vcxproj file:

    <ClCompile>
      <AdditionalOptions>$(ExternalCompilerOptions) ... </AdditionalOptions>
    </ClCompile>

This works for me with VS 2010. We drive msbuild from various build scripts, so the environment variable ugliness is hidden a bit. Note that I have not tested if this works when you need to set the define to specific value ( /DACTIVATE=1 ). I think it would work, but I'm concerned about having multiple '='s in there.

H^2

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