IStream::CopyTo

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11/18/2015

A version of this page is also available for

4/8/2010

This method copies a specified number of bytes from the current seek pointer in the stream to the current seek pointer in another stream.

Syntax

HRESULT CopyTo( 
  IStream* pstm, 
  ULARGE_INTEGER cb, 
  ULARGE_INTEGER* pcbRead, 
  ULARGE_INTEGER* pcbWritten 
);

Parameters

pstm
[in] Pointer to the destination stream.

The stream pointed to by pstm can be a new stream or a clone of the source stream.

cb
[in] Number of bytes to copy from the source stream.

pcbRead
[out] Pointer to the location where this method writes the actual number of bytes read from the source.

You can set this pointer to NULL to indicate that you are not interested in this value. In this case, this method does not provide the actual number of bytes read.

pcbWritten
[out] Pointer to the location where this method writes the actual number of bytes written to the destination.

You can set this pointer to NULL to indicate that you are not interested in this value. In this case, this method does not provide the actual number of bytes written.

Return Value

The following table shows the return values for this method.

Value	Description
S_OK	The stream object was successfully copied.
E_PENDING	Asynchronous Storage only: Part or all of the data to be copied is currently unavailable.
STG_E_INVALIDPOINTER	The value of one of the pointer parameters is not valid.
STG_E_MEDIUMFULL	The stream is not copied because there is no space left on the storage device.
STG_E_REVERTED	The object has been invalidated by a revert operation above it in the transaction tree.

Remarks

This method copies the specified bytes from one stream to another. The seek pointer in each stream instance is adjusted for the number of bytes read or written.

The destination stream can be a clone of the source stream created by calling the IStream::Clone method.

If IStream::CopyTo returns an error, you cannot assume that the seek pointers are valid for either the source or destination. Additionally, the values of pcbRead and pcbWritten are not meaningful even though they are returned.

If IStream::CopyTo returns successfully, the actual number of bytes read and written are the same.

To copy the remainder of the source from the current seek pointer, specify the maximum large integer value for the cb parameter.

If the seek pointer is the beginning of the stream, this technique copies the entire stream.

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

Requirements

Header	objidl.h, objidl.idl
Library	ole32.lib, uuid.lib
Windows Embedded CE	Windows CE 2.0 and later
Windows Mobile	Windows Mobile Version 5.0 and later

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