Michael Miles-Stimson Michael Miles-Stimson - 3 months ago 14
C# Question

How to use #if to decide which platform is being compiled for in C#

In C++ there are predefined macros:

#if defined(_M_X64) || defined(__amd64__)
// Building for 64bit target
const unsigned long MaxGulpSize = 1048576 * 128;// megabyte = 1048576;
const unsigned long MaxRecsCopy = 1048576 * 16;
#else
const unsigned long MaxGulpSize = 1048576 * 8;// megabyte = 1048576;
const unsigned long MaxRecsCopy = 1048576;
#endif


Which allows me to set constants to control the amount of memory that will be used.

Of course I can define a preprocessor variable verbatim:

#define Is64bit 1

using System;
using System.Collections.Generic;


-later-

#if Is64bit
// Building for 64bit target
const long MaxGulpSize = 1048576 * 128;// megabyte = 1048576;
const long MaxRecsCopy = 1048576 * 16;
#else
const long MaxGulpSize = 1048576 * 8;// megabyte = 1048576;
const long MaxRecsCopy = 1048576;
#endif


I cannot find a way to detect the platform based on the values set in the configuration manager which would allow for command line building:

set de=C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\devenv.exe
set sol=E:\Some\Path\to\my.sln
"%de%" %sol% /build "Release|x86"
"%de%" %sol% /build "Release|x64"


Is there a way to detect this or will I have to build, change platform and build again?

Answer

You can add any constants you want to the .csproj file. These can be put into conditional property groups like the one below.

 <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x64'">
    <DefineConstants>TRACE;X64</DefineConstants>
    ...
 </PropertyGroup>

For my Release x64 build, I have defined a X64 constant that I can use like this:

#if X64

#endif