Accessing COM interface from C or C++ in Windows environment

Answer 1

I would suggest looking into ATL if you are using C++, and using C++ if using C. It is very easy to use the #import construct to access COM objects in DLLs or EXEs.

Answer 2

Actually, you will need to instantiate the object using the COM interface.

This is fairly complicated, more than we can just answer here.

here is a good primer: http://www.codeproject.com/KB/COM/comintro.aspx

Another one: http://www.codeguru.com/cpp/com-tech/activex/tutorials/article.php/c5567

Answer 3

There is a wonderful article at Microsoft that seems to address this exact question. If you want to stick with straight C++ (i.e. MFC/ATL), you should check out the article as it has loads of sample code:

How to automate Excel from C++ without using MFC or #import

Answer 4

You absolutely don't need ATL.

See MSDN and the KB, where there are dozens of complete samples

And search on Google Groups for this question which has been answered hundreds of times for 15 years...