IStream::Clone method (objidl.h)

The Clone method creates a new stream object with its own seek pointer that references the same bytes as the original stream.


  [out] IStream **ppstm


[out] ppstm

When successful, pointer to the location of an IStream pointer to the new stream object. If an error occurs, this parameter is NULL.

Return value

This method can return one of these values.

Return code Description
S_OK The stream was successfully cloned.
E_PENDING Asynchronous Storage only: Part or all of the stream's data is currently unavailable.
STG_E_INSUFFICIENTMEMORY The stream was not cloned due to a lack of memory.
STG_E_INVALIDPOINTER The ppStm pointer is not valid.
STG_E_REVERTED The object has been invalidated by a revert operation above it in the transaction tree.


The Clone method creates a new stream object for accessing the same bytes but using a separate seek pointer. The new stream object sees the same data as the source-stream object. Changes written to one object are immediately visible in the other. Range locking is shared between the stream objects.

The initial setting of the seek pointer in the cloned stream instance is the same as the current setting of the seek pointer in the original stream at the time of the clone operation.


Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps | UWP apps]
Minimum supported server Windows 2000 Server [desktop apps | UWP apps]
Target Platform Windows
Header objidl.h
Library Uuid.lib
DLL Ole32.dll

See also

IStream - Compound File Implementation