Vlad,
>If it uses CStrings, than it's C++...
Yes CString is the MFC string class.
>I don't believe that a function that returns a CString can be exported as C standard.
I've never written a C++ DLL routine that returns a string. Most of the time I pass a string reference to the DLL, so I can let VFP preallocate the buffer, but I'd guess that it isn't really a problem if you just assign a CString return value into the VPF memvar, I might just have to test this later.
But I know that my VFP Ole server returns a VFP string and the C++ code recieves it as a CString. VC++ seems pretty good at casting CStrings in and out.