OVERLAPPED  1BGZJY 

The OVERLAPPED structure contains information used in asynchronous input and output (I/O).

typedef struct _OVERLAPPED {  // o

    DWORD  Internal;

    DWORD  InternalHigh;

    DWORD  Offset;

    DWORD  OffsetHigh;

    HANDLE hEvent;

} OVERLAPPED;

Members

Internal

Reserved for operating system use. This member, which specifies a system-dependent status, is valid when the GetOverlappedResultKCZ7OZ function returns without setting the extended error information to ERROR_IO_PENDING.

InternalHigh

Reserved for operating system use. This member, which specifies the length of the data transferred, is valid when the GetOverlappedResult function returns TRUE.

Offset

Specifies a file position at which to start the transfer. The file position is a byte offset from the start of the file. The calling process sets this member before calling the ReadFileCJND8P or WriteFileG0SOX_ function. This member is ignored when reading from or writing to named pipes and communications devices.

OffsetHigh

Specifies the high word of the byte offset at which to start the transfer. This member is ignored when reading from or writing to named pipes and communications devices.

hEvent

Identifies an event set to the signaled state when the transfer has been completed. The calling process sets this member before calling the ReadFileCJND8P, WriteFileG0SOX_, ConnectNamedPipeKSA3SM, or TransactNamedPipe1NUXHMK function.

Remarks

You can use the HasOverlappedIoCompleted macro to determine whether an asynchronous I/O operation has completed. You can use the CancelIo function to cancel an asynchronous I/O operation.

See Also