# IStream::Write

Writes a specified number from bytes into the stream object starting at the current seek pointer.

HRESULT Write(

void const* pv, | //Pointer to buffer from which stream is written
ULONG cb, | //Specifies the number of bytes to write
ULONG * pcbWritten | //Specifies the actual number of bytes written
); |

Parameters

pv
  [in] Points to the buffer from which the stream should be written.
cb
  [in] The number of bytes of data to attempt to write into the stream.
pcbWritten
  [out] Pointer to a location where this method writes the actual number of bytes written to the stream object. The caller can set this pointer to NULL, in which case, this method does not provide the actual number of bytes written.

Return Values

S_OK
  The data was successfully written into the stream object.
E_PENDING
  Asynchronous Storage only: Part or all of the data to be written is currently unavailable. For more information see IFillLockBytes and Asynchronous Storage.
STG_E_MEDIUMFULL
  The write operation was not completed because there is no space left on the storage device.
STG_E_ACCESSDENIED
  The caller does not have sufficient permissions for writing this stream object.
STG_E_CANTSAVE
  Data cannot be written for reasons other than no access or space.
STG_E_INVALIDPOINTER
  One of the pointer values is invalid.
STG_E_REVERTED
  The object has been invalidated by a revert operation above it in the transaction tree.
STG_E_WRITEFAULT
  The write operation was not completed due to a disk error.

Remarks

IStream::Write writes the specified data to a stream object. The seek pointer is adjusted for the number of bytes actually written. The number of bytes actually written is returned in the pcbWrite parameter. If the byte count is zero bytes, the write operation has no effect.

If the seek pointer is currently past the end of the stream and the byte count is non-zero, this method increases the size of the stream to the seek pointer and writes the specified bytes starting at the seek pointer. The fill bytes written to the stream are not initialized to any particular value. This is the same as the end-of-file behavior in the MS-DOS FAT file system.

With a zero byte count and a seek pointer past the end of the stream, this method does not create the fill bytes to increase the stream to the seek pointer. In this case, you must call the IStream::SetSize method to increase the size of the stream and write the fill bytes.

The pcbWrite parameter can have a value even if an error occurs.

In the OLE-provided implementation, stream objects are not sparse. Any fill bytes are eventually allocated on the disk and assigned to the stream.

See Also

IStream - Compound File Implementation