Possible Duplicate:
Using C++ Class DLL in C# Application
I try to failed to add reference to add c++ dll in c#
if you have any other method to add or use c++ dll in c#. how can we use?
Where do i mistake to add dll in my c# project?
Thanks in advance
For using native C++ libraries in C#, you mostly will have to create a C++/CLI wrapper for that. P/Invoke is ok as long as the API of your DLL contains just simple C-like functions, but when the API contains real C++ classes, C++/CLI ist much better for that task.
You don't add a reference to a C++ library, that's for .NET assemblies only. What you need is platform interop using P/Invoke. MSDN has a bunch of information here:-
http://msdn.microsoft.com/en-us/library/aa288468(VS.71).aspx
It basically means you have to write method stubs that call your exported functions in the external library.
There is also the C++/CLI way which can be better depending on your C++ project setup, but personally I prefer the traditional Windows API function export way.