IStream::CopyTo
Copies a
specified number of bytes from the current seek pointer in the stream to the
current seek pointer in another stream.
HRESULT CopyTo(
|
IStream * pstm, |
//Points
to the destination stream |
|
ULARGE_INTEGER cb, |
//Specifies
the number of bytes to copy |
|
ULARGE_INTEGER * pcbRead, |
//Pointer
to the actual number of bytes read from the source |
|
ULARGE_INTEGER * pcbWritten |
//Pointer
to the actual number of bytes written to the destination |
|
); |
|
Parameters
pstm
[in] Points
to the destination stream. The stream pointed to by pstm can be a new
stream or a clone of the source stream.
cb
[in]
Specifies the 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 Values
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.
For more information see IFillLockBytes and Asynchronous Storage.
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. This
method is equivalent to reading cb bytes into memory using IStream::Read and then immediately
writing them to the destination stream using IStream::Write, although IStream::CopyTo
will be more efficient.
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.
See Also
IStream
- Compound File Implementation, IStream::Read, IStream::Write, IStream::Clone