C++ Dll in VC#

The only other way would be to convert the dll into a COM component and then use it from C# using COM interop.

However, the best way of using a non-COM C++ dll from C# is to wrap it in a mixed mode C++/CLI dll and then add a reference to the latter to your C# project.

I don't know whether you've seen it already but the following is a very good article on this technique which has recently been published on this site:

http://www.c-sharpcorner.com/UploadFile/SamTomato/managed-cpp-wrapper-for-unmanaged-code/