Maybe [OT] Creating Object in libraries

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Hi everybody,
I'm new in DLL Libraries development, I made my first
Dll with some functions. Now, I'd like to know (maybe there's a conceptual
mistake in my head) how can i build a collection on Classes in my DLL and
using them in my applications? Let explain myself:

If I write a function, I can export it by:

extern "C" (dllexport)... ... ....

While, If I've got a Library of classes (TFile, TMyClass, TClock,
TNewsgroup, etc..), how can I use them outside of my library?

Thanks everybody
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