IStreamAsync::WriteAsync method (shobjidl.h)

Article
02/22/2024

Writes information to a stream asynchronously. For example, the Shell implements this method on file items when transferring them asynchronously.

Syntax

HRESULT WriteAsync(
  [in]  const void   *lpBuffer,
  [in]  DWORD        cb,
  [out] LPDWORD      pcbWritten,
  [in]  LPOVERLAPPED lpOverlapped
);

Parameters

[in] lpBuffer

Type: const void*

A pointer to a buffer of size cb bytes that contains the information to be written to the stream.

[in] cb

Type: DWORD

The size of the buffer pointed to by lpBuffer, in bytes.

[out] pcbWritten

Type: LPDWORD

Pointer to a DWORD value that, when the method returns successfully, states the actual number of bytes written to the stream. This value can be NULL if this information is not needed.

[in] lpOverlapped

Type: LPOVERLAPPED

A pointer to an OVERLAPPED structure that contains information used in the asynchronous write operation.

Return value

Type: HRESULT

If this method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

WriteAsync should reset the event specified by the hEvent member of the OVERLAPPED structure to a nonsignaled state when it begins the input/output (I/O) operation.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
Target Platform	Windows
Header	shobjidl.h

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