Calling DLL from QM

[lionking]

Thanks a lot for your samples and explanations.
I found that the extern "C" is simpler to use than the COM interface method.
The COM interface is "way beyond" my knowledge :-)
But it's interesting to see that it could be done by using it.

So far I've succeeded with the extern "C" method but with the COM interface I still have errors for the keywords:
"IUnknown" = error not a class or struct name
"STDMETHODIMP" = error identifier STDMETHODIMP is undefined

1/ Do I miss any header file for "STDMETHODIMP"?

2/ What tool do you use to get this ID?:
#define IID_IMathFuncs __uuidof(IMathFuncs)
__interface __declspec(uuid("1DD0DD58-59C7-4308-93B8-40EEDEDE2415")) //replace this with your generated GUID