Windows Mobile 6.5
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This interface enables clients to get pointers to other interfaces on a specified object through the IUnknown::QueryInterface method, and manage the existence of the object through the IUnknown::AddRef and IUnknown::Release methods.

All other COM interfaces are inherited, directly or indirectly, from IUnknown.

Therefore, the three methods in IUnknown are the first entries in the vtable for every interface.

The following table shows the methods for this interface in alphabetical order.

Method Description


Increments the reference count for an interface on an object.

It should be called for every new copy of a pointer to an interface on a specified object.


Returns a pointer to a specified interface on an object to which a client currently holds an interface pointer.

This method must call IUnknown::AddRef on the pointer it returns.


Decrements the reference count for the calling interface on a object.

If the reference count on the object falls to zero, the object is freed from memory.

To determine whether the platform supports this interface, see Determining Supported COM APIs.

Headerunknwn.h, unknwn.idl
Libraryole32.lib, uuid.lib
Windows Embedded CEWindows CE 1.0 and later
Windows MobileWindows Mobile Version 5.0 and later