PurgeComm function

Discards all characters from the output or input buffer of a specified communications resource. It can also terminate pending read or write operations on the resource.

Syntax


BOOL WINAPI PurgeComm(
  _In_  HANDLE hFile,
  _In_  DWORD dwFlags
);

Parameters

hFile [in]

A handle to the communications resource. The CreateFile function returns this handle.

dwFlags [in]

This parameter can be one or more of the following values.

ValueMeaning
PURGE_RXABORT
0x0002

Terminates all outstanding overlapped read operations and returns immediately, even if the read operations have not been completed.

PURGE_RXCLEAR
0x0008

Clears the input buffer (if the device driver has one).

PURGE_TXABORT
0x0001

Terminates all outstanding overlapped write operations and returns immediately, even if the write operations have not been completed.

PURGE_TXCLEAR
0x0004

Clears the output buffer (if the device driver has one).

 

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

If a thread uses PurgeComm to flush an output buffer, the deleted characters are not transmitted. To empty the output buffer while ensuring that the contents are transmitted, call the FlushFileBuffers function (a synchronous operation). Note, however, that FlushFileBuffers is subject to flow control but not to write time-outs, and it will not return until all pending write operations have been transmitted.

Requirements

Minimum supported client

Windows XP

Minimum supported server

Windows Server 2003

Header

Winbase.h (include Windows.h)

Library

Kernel32.lib

DLL

Kernel32.dll

See also

Communications Functions
Communications Resources
CreateFile

 

 

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