Thread: Pointer To Functions In COM Confusing

Hi I am not one for using virtual inheritance or pointers to functions if I can help it, but I am trying to start to learn the basics of direct x and it was recommended i knew a bit about COM first. I was very happy with it until I got to this function which confused me.

Code:

HRESULT __stdcall CCOM_OBJECT::QueryInterface(const IID &iid, void **iface)
{
	// this function basically casts the this pointer or the iunknown
	// pointer to the interface requested, notice the comparison with
	// the GUIDs generated and defined in the beginning of the progra,

	// requestiong the IUNKNOWN base interface
	if (iid == IID_IUnknown)
	{
		cout << "Requesting IUnknown interface" << endl;
		*iface = (IX*)this;

	}

	if (iid == IID_IX)
	{
		cout << "Requestiong IX interface" << endl;
		*iface = (IX*)this;
	}
	else
	{
		if (iid == IID_IY)
		{
			cout << "Requestion IY interface" << endl;
			*iface = (IY*)this;
		}
		else
		{
			cout << "Requesting Unknown interface!" << endl;
			*iface = NULL;
			return(E_NOINTERFACE);
		} // end else
	}
	// if everthing went well cast pointer to IUNKNOWN and call addref()
	((IUnknown *)(*iface))->AddRef();

	return (S_OK);

}

Now my problem is I have no idea what parameter this is
void **iface
at first i thought it was a pointer to a function but that cant be because it gets set to *iface = (IY*)this; which by its nature isn't a function so im completely confused. Even by the line that calls the function which is
punknown->QueryInterface(IID_IY, (void**)&piy);

Somebody please help

So should QueryInterface(const IID &iid, void **iface)
really have the void * in brackets so its
QueryInterface(const IID &iid, (void*)*iface)
like a standard c type cast?

Oh okay thanks mate I think I get it many thanks