C# Preprocessor with Operating System

CallDifferenceByOS.cs

#if Windows
  Console.WriteLine("Windows!");
#elif Linux
  Console.WriteLine("Linuxw!");
#elif OSX
  Console.WriteLine("osx!");
#endif

project.csproj

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <RootNamespace>notepad_asp</RootNamespace>
  </PropertyGroup>

  <PropertyGroup>
    <DefineConstants Condition="'$([System.Runtime.InteropServices.RuntimeInformation]::IsOSPlatform($([System.Runtime.InteropServices.OSPlatform]::Windows)))' == 'true'">Windows</DefineConstants>
    <DefineConstants Condition="'$([System.Runtime.InteropServices.RuntimeInformation]::IsOSPlatform($([System.Runtime.InteropServices.OSPlatform]::OSX)))' == 'true'">OSX</DefineConstants>
    <DefineConstants Condition="'$([System.Runtime.InteropServices.RuntimeInformation]::IsOSPlatform($([System.Runtime.InteropServices.OSPlatform]::Linux)))' == 'true'">Linux</DefineConstants>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="System.Diagnostics.PerformanceCounter" Version="6.0.1" />
  </ItemGroup>


</Project>