C# Directive to indicate 32-bit or 64-bit build

Question

Is there some sort of C# directive to use when using a development machine (32-bit or 64-bit) that says something to the effect of:

if (32-bit Vista)
    // set a property to true
else if (64-bit Vista)
    // set a property to false

but I want to do this in Visual Studio as I have an application I'm working on that needs to be tested in 32/64 bit versions of Vista.

Is something like this possible?

Solution 1

Can you do it at runtime?

if (IntPtr.Size == 4)
  // 32 bit
else if (IntPtr.Size == 8)
  // 64 bit

Solution 2

There are two conditions to be aware of with 64-bit. First is the OS 64-bit, and second is the application running in 64-bit. If you're only concerned about the application itself you can use the following:

if( IntPtr.Size == 8 )
   // Do 64-bit stuff
else
   // Do 32-bit

At runtime, the JIT compiler can optimize away the false conditional because the IntPtr.Size property is constant.

Incidentally, to check if the OS is 64-bit we use the following

if( Environment.GetEnvironmentVariable( "PROCESSOR_ARCHITEW6432" ) != null )
    // OS is 64-bit;
else
    // OS is 32-bit

Solution 3

You can use a #if directive and set the value as a compiler switch (or in the project settings):

 #if VISTA64
     ...
 #else
     ...
 #endif

and compile with:

 csc /d:VISTA64 file1.cs 

when compiling a 64 bit build.

Solution 4

I am not sure if this is what you are looking for but I check the IntPtr.Size to detect 32bit versus 64bit runtime. Note that this tells you the runtime environment, you might be running in WOW64

if (IntPtr.Size == 4)
{
    //32 bit
}
else if (IntPtr.Size == 8)
{
    //64 bit
}
else
{
    //the future
}

Solution 5

What I use in my C# code is IntPtr.Size, it equals 4 on 32bit and 8 on 64bit:

string framework = (IntPtr.Size == 8) ? "Framework64" : "Framework";

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Comments

[Neil N]

In reality, compiling for "Any CPU" while in 64 bit mode prevents you from deploying to 32 bit mode, unless MS fixed this bug in VS2008... but last I tried, you had to specify 32 bit.

[Paul Alexander]

@Neil: I do all my development on a 64-bit machine and never seen this issue.

[Neil N]

From an MS MVP: "the problem is deployment. MSI files / Deployment projects need to be targeted at one platform. This means if you want x86/x64 deployment, you compile your DLL's once, then build two deployment projects. This pattern also holds true for Merge Modules and such." eggheadcafe.com/…

[Neil N]

I wouls actually say the problem is wider than he states there.. but not everyone will run into these issues.

[Paul Alexander]

That still only applies when you explicitly target specific platforms. The assemblies still target Any CPU. The MSI Project might specify 32/64-bit. In practice the MSI can simply be 32-bit and the app will still run 64-bit once installed.