IUnknown::QueryInterface

Article
08/28/2006

The QueryInterface method returns a pointer to a specified interface on an object to which a client currently holds an interface pointer. This method must call the IUnknown::AddRef method on the pointer it returns.

Note The QueryInterface method is not implemented on many Windows Mobile-based MAPI interfaces for Pocket PC and Smartphone 2002 or Windows Mobile 2003.

Syntax

HRESULT QueryInterface(
  REFIID iid,
  void ** ppvObject
);

Parameters

iid
[in] Identifier of the interface being requested.
ppvObject
[out] Address of the pointer variable that receives the interface pointer requested in riid. Upon successful return, *ppvObject contains the requested interface pointer to the object. If the object does not support the interface specified in iid, *ppvObject is set to NULL.

Return Values

S_OK
Indicates that the interface specified by iid is supported, and the method returned successfully.
E_NOINTERFACE
Indicates that the interface specified by iid is not supported.
E_NOTIMPL
Indicates that QueryInterface is not implemented on the interface object from which it is being called.

Remarks

For more information about this method, see IUnknown::QueryInterface in the Window CE documentation.

Requirements

Pocket PC: Pocket PC 2002 and later
Smartphone: Smartphone 2002 and later
OS Versions: Windows CE 3.0 and later
Header: unknwn.h