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c#64-bitpinvoke32-bituser32

C# PInvoking user32.dll on a 64 bit system

Is it wrong to pinvoke user32.dll on 64 bit Windows, from a 64 bit app? I've done this successfully a number of times and never had an error, but it seems contradictory. Should I look for user64.dll instead?

Solution

  • The name user32.dll is misleading. It's the 64 bit version of user32.dll you're calling. The 64 bit version is located at %windir%\System32\user32.dll.

    A 32-bit version is included for compatibility with 32-bit applications. It's located at %windir%\SysWOW64\user32.dll. You can inspect them using the dumpbin utility:

    System32\user32.dll:

    FILE HEADER VALUES
        8664 machine (x64)

    SysWOW64\user32.dll:

    FILE HEADER VALUES
         14C machine (x86)