I’m using Visual Studio 2008 to build a Solution with two Projects: a C# Console App and a C++ DLL. I want the app to call a function from the dll using P/Invoke. Therefore I’m trying to add the dll as a Reference to the C# app. But when I try the Add Reference command, Visual Studio won’t let me do it unless I set the /clr property on the dll (under Configuration Properties:General). Now, I thought that P/Invoke could handle plain-old win32 dlls. Indeed, if I build my dll without /clr and just copy it by hand to bin/Debug, then the app runs fine. So why is /clr required to add the dll as a reference? And if VS won’t let me add it, is there some (clean) workaround so that my app finds the dll?
I see that someone had a similar issue here (though with a 3rd-party dll):
Unable to add a DLL Reference to VS 2008 The answer he got was to build a wrapper. But this isn’t really necessary, since the app can use the dll just fine; it’s just the Add Reference step that doesn’t work. And besides, won’t the wrapper code need a reference to the dll, raising the same problem as before? I’d really like an answer that doesn’t involve writing a wrapper at all.
Why not just add a post-build step to copy your unmanaged DLL to your project directory? You don’t need a “reference” to be able to refer to an unmanaged DLL, and it sounds like the only problem you’re experiencing is due to the file not being automatically copied into the search path.