Question

tlb file(using regasm) is made from a dll(using c# code), and i can use this in c++ using #import. and everything is working fine.
Is there a way, i can use this in C language? I just found that #import is c++ specific. So, can someone please tell me how can i use in my C program?

my main intention is to use COM DLL developed in C# in my C program.

Thanks & Rgds,
~calvin

Answer 1

COM programming in C is very painful, but not impossible. The buck stops here though. The point of a type library is to have a tool auto-generate the COM interface and co-class declarations so that you can use them in your code. Quite similar to a .h file, but language independent. The .NET equivalent is the metadata in an assembly.

Problem is, the tooling isn’t available to convert a .tlb to C declarations. I’m sure you are familiar with #import, that’s what gets used in MSVC. But it generates C++ code, smart pointers that help you create the COM object, call its interface methods and deal with errors. If there is a tool available that generates C then it is a very well hidden secret.

One trick jumps to mind, you can use OleView.exe, File + View TypeLib to view the contents of the type library. This view is decompiled into IDL, the interface definition language. You can copy and paste this text into an .idl file and compile it with midl.exe with the /header command line option. This generates a .h file that contains both C++ and the C declarations for the interfaces. Ought to get you close, just make sure that the type library is reasonably stable so you don’t have to do this very often.