.NET – How to tell if a DLL is 32bit or 64bit

So in the world of MS Windows software development, the bitness of DLLs (64bit vs 32bit) is the new DLL Hell!! It is slightly annoying that Microsoft eventually dug itself out of decades of DLL hell just to create a new hellish DLL vista – anyway there’s nothing to be done.

API vendors will often have 2 versions of their API, a 32bit one and a 64bit one, sometimes if you are really unlucky they will name their assemblies and DLLs using the same names for both platforms so there will be no way to easily tell if a DLL is 32bit or 64bit just by looking at the file name.

So how do you figure out the bitness of a DLL when you are trying to debug and fix .NET ‘Incorrect Format’ errors?

Annoyingly it turns out that there is no easy way to do this through windows. There is, however, a nice little tool by Silurian Software that integrates into windows explorer’s file properties pages called InspectEye, it gives you loads of info about an EXE or DLL including whether it’s 32 or 64 bit! It worked nicely for us anyway although I haven’t looked at the rest of the software’s features yet…

The tool can be downloaded from here:

http://www.silurian.com/win32/inspect.htm