I have C++ code that is written with the Qt library.
I compile it with
\clr and when I add a 'DLL' file to C# reference, I have no class and namespace that declare in it 'dll'.
Where is problem?
I don't know if you resolve your problem. You need to make a C++/CLI class in order to use it in your C# code. In the code of this class you can make unmanaged calls but you need to return managed type. You can find information about C++/CLI and managed/unmanaged context on msdn.