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c#visual-studio-2019projectsolutionpreprocessor-directive

Defining C# preprocessor directive at the Solution level

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Is it possible in C# to define a preprocessor directive at the solution level rather than the project level.

Motivation: I have a common library, and there are two solutions that need it. I want the preprocessor directive to be present in one, and not the other, but since the library is at the project level, if I define the preprocessor directive at the project level, this obviously won't work.

Solution

  • You can do this with a Directory.Build.props file, and put it at the root of your solution. Inside the file you can specify DefineConstants option:

    <Project>
  <PropertyGroup>
    <DefineConstants>MY_DIRECTIVE</DefineConstants>
  </PropertyGroup>
</Project>