Abstract class (IDispatch) in a C structure

[Overlord]

I have a C structure (not my code), which compiles without errors on a C compiler

typedef struct{
	IDispatch		dispatchObj;
	DWORD			refCount;
} _IDispatchEx;

But when compiling in C++, I get this error:

'IDispatch' : cannot instantiate abstract class

because IDispatch is an abstract class (COM). I don't understand how it can be declared in C, since C doesn't support classes at all, but the problem is that I need to use this structure in my C++ program.

How should I change it to work in my C++ project?

p.s. If I declared dispatchObj as a pointer (IDispatch *dispatchObj; ), the structure wouldn't work as intended (or would it?).

Thanks for any help.