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Determining Which Interface an Object Supports
The QueryInterface method lets an application query an object to determine which interfaces it
supports. The sample application sets the ppv pointer to the current interface.
STDMETHODIMP CAVIFileCF::QueryInterface(
const IID FAR& iid,
void FAR* FAR* ppv)
{
if (iid == IID_IUnknown)
*ppv = this; // set the interface pointer
// to this instance
else if (iid == IID_IClassFactory)
*ppv = this; // second chance to set the
// interface pointer to this
// instance
else
return ResultFromScode(E_NOINTERFACE);
AddRef(); //Increment the reference count
return NULL;
}
Related Links
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Microsoft Windows Telephony API (TAPI) Programmer's Reference (tapi.hlp)
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