The Windows Sockets WSAGetOverlappedResult function returns the results of an overlapped operation on the specified socket.

BOOL WSAGetOverlappedResult (



LPDWORD lpcbTransfer,

BOOL fWait,

LPDWORD lpdwFlags




[in] Identifies the socket. This is the same socket that was specified when the overlapped operation was started by a call to WSARecv, WSARecvFrom, WSASend, WSASendTo, or WSAIoctl.


[in] Points to a WSAOVERLAPPED structure that was specified when the overlapped operation was started.


[out] Points to a 32-bit variable that receives the number of bytes that were actually transferred by a send or receive operation, or by WSAIoctl.


[in] Specifies whether the function should wait for the pending overlapped operation to complete. If TRUE, the function does not return until the operation has been completed. If FALSE and the operation is still pending, the function returns FALSE and the WSAGetLastError function returns WSA_IO_INCOMPLETE.


[out] Points to a 32-bit variable that will receive one or more flags that supplement the completion status. If the overlapped operation was initiated through WSARecv or WSARecvFrom, this parameter will contain the results value for lpFlags parameter.


The results reported by the WSAGetOverlappedResult function are those of the specified socket's last overlapped operation to which the specified WSAOVERLAPPED structure was provided, and for which the operation's results were pending. A pending operation is indicated when the function that started the operation returns FALSE, and the WSAGetLastError function returns WSA_IO_PENDING. When an I/O operation is pending, the function that started the operation resets the hEvent member of the WSAOVERLAPPED structure to the nonsignaled state. Then when the pending operation has been completed, the system sets the event object to the signaled state.

If the fWait parameter is TRUE, WSAGetOverlappedResult determines whether the pending operation has been completed by waiting for the event object to be in the signaled state.

Return Values

If WSAGetOverlappedResult succeeds, the return value is TRUE. This means that the overlapped operation has completed successfully and that the value pointed to by lpcbTransfer has been updated. If WSAGetOverlappedResult returns FALSE, this means that either the overlapped operation has not completed or the overlapped operation completed but with errors, or that completion status could not be determined due to errors in one or more parameters to WSAGetOverlappedResult. On failure, the value pointed to by lpcbTransfer will not be updated. Use WSAGetLastError to determine the cause of the failure (either of WSAGetOverlappedResult or of the associated overlapped operation).

Error Codes

A successful WSAStartup must occur before using this function.
The network subsystem has failed.
The descriptor is not a socket.
The hEvent field of the WSAOVERLAPPED structure does not contain a valid event object handle.
One of the parameters is unacceptable.
fWait is FALSE and the I/O operation has not yet completed.

See Also

, WSAConnect, WSACreateEvent, WSAIoctl, WSARecv, WSARecvFrom, WSASend, WSASendTo, WSAWaitForMultipleEvents

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