I am trying include c++ library (DLL) in my c# project but every time I do that I get following error message in VS2008, any suggestions?
EDIT: It's a C++ MFC DLL
--------------------------- Microsoft Visual Studio --------------------------- A reference to 'C:\Users\cholachaguddapv\Desktop\imaging.dll' could not be added. Please make sure that the file is accessible, and that it is a valid assembly or COM component.
If it is a "normal" DLL (not COM, not managed C++), you cannot add a reference like this. You have to add p/invoke signatures (external static method definitions) for the exports you want to call in your DLL.
[DllImport("yourdll.dll")]
public static extern int ExportToCall(int argument);
Have a look at the DllImport attribute in the online help.
If it's a straight C++ library then it's not possible to reference it in this way.
You have two options, you can compile the C++ library as an assembly an expose the unmanaged code with a C++/CLI wrapper.
-or-
You can use some p/invoke calls if the library exposes it's functionality via a C API.
Could you expand the question a bit to include some details about how you normally call imaging.dll from c++?
if it is a unmanaged dll you cannot add a reference to it. You have to invoke it using pinvoke or the likes of it:
public classFoo
{
[DllImport("myunmanaged.dll", CharSet = CharSet.Ansi)]
private extern static int UnmanagedFunction(int type, int dest);
}
If you wanna convert it to a managed dll take a look here: http://msdn.microsoft.com/en-us/library/aa446538.aspx
If you wanna know some more about pinvoke and dllimport take a look here: http://msdn.microsoft.com/en-us/library/aa288468.aspx
Cheers
Calling convention and memory model difference between managed code (C#) and non-Managed code (WIn32 C++) make them incompatible.
However, .NET include a bridge technology for COM objects, so if you imaging DLL were a COM object, it could be made to work. It is, however, apparently not a COM object.
If it's a clean C++ DLL where you only export C compatible functions, then you can use P/Invoke to use those functions. If you turn that C++ DLL into a COM DLL with a Type Library, using it is even easier: you can import the type library into .NET and .NET wrappers (called Runtime Callable Wrappers) are created for you.
