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/platform (Visual Basic)

Specifies which platform version of common language runtime (CLR) can run the output file.

/platform:{ x86 | x64 | Itanium | arm | anycpu | anycpu32bitpreferred }

Term

Definition

x86

Compiles your assembly to be run by the 32-bit, x86-compatible CLR.

x64

Compiles your assembly to be run by the 64-bit CLR on a computer that supports the AMD64 or EM64T instruction set.

Itanium

Compiles your assembly to be run by the 64-bit CLR on a computer with an Itanium processor.

arm

Compiles your assembly to be run on a computer with an ARM (Advanced RISC Machine) processor.

anycpu

Compiles your assembly to run on any platform. The application will run as a 32-bit application on 32-bit versions of Windows and as a 64-bit application on 64-bit versions of Windows. This flag is the default value.

anycpu32bitpreferred

Compiles your assembly to run on any platform. The application will run as a 32-bit application on both 32-bit and 64-bit versions of Windows. This flag is valid only for executables (.EXE) and requires .NET Framework 4.5.

Use the /platform option to specify the type of processor targeted by the output file.

In general, .NET Framework assemblies written in Visual Basic will run the same regardless of the platform. However, there are some cases that behave differently on different platforms. These common cases are:

  • Structures that contain members that change size depending on the platform, such as any pointer type.

  • Pointer arithmetic that includes constant sizes.

  • Incorrect platform invoke or COM declarations that use Integer for handles instead of IntPtr.

  • Casting IntPtr to Integer.

  • Using platform invoke or COM interop with components that do not exist on all platforms.

The /platform option will mitigate some issues if you know you have made assumptions about the architecture your code will run on. Specifically:

  • If you decide to target a 64-bit platform, and the application is run on a 32-bit machine, the error message comes much earlier and is more targeted at the problem than the error that occurs without using this switch.

  • If you set the x86 flag on the option and the application is subsequently run on a 64-bit machine, the application will run in the WOW subsystem instead of running natively.

On a 64-bit Windows operating system:

  • Assemblies compiled with /platform:x86 will execute on the 32-bit CLR running under WOW64.

  • Executables compiled with the /platform:anycpu will execute on the 64-bit CLR.

  • A DLL compiled with the /platform:anycpu will execute on the same CLR as the process into which it loaded.

  • Executables that are compiled with /platform:anycpu32bitpreferred will execute on the 32-bit CLR.

For more information about how to develop an application to run on a 64-bit version of Windows, see 64-bit Applications.

To set /platform in the Visual Studio IDE

  1. In Solution Explorer, choose the project, open the Project menu, and then click Properties.

    For more information, see Introduction to the Project Designer.

  2. On the Compile tab, select or clear the Prefer 32-bit check box, or, in the Target CPU list, choose a value.

    For more information, see Compile Page, Project Designer (Visual Basic).

The following example illustrates how to use the /platform compiler option.

vbc /platform:x86 myFile.vb
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