WriteFile操作时返回87错误

调用 WriteFile写数据时出错，用GetLastError得到错误代码为87（无效参数）。 

代码片段如下：

  if ((!WriteFile(        m_hDevEx,        pBuf,        size,        &WriteBytes,        &Overlapped)) &&        (GetLastError() != ERROR_IO_PENDING))    {        OutputDebugString("Write error\n");        return false;    }

 问题出在最后一个参数Overlapped，初始化是这样的：

    OVERLAPPED Overlapped;    Overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

这种初始化在ReadFile时时没有问题的，而WriteFile时需要将该结构体中的Offset，OffsetHigh两个参数设置成零，即:

    OVERLAPPED    Overlapped;    Overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);    Overlapped.Offset = 0;    Overlapped.OffsetHigh = 0; 

以上这样初始化之后，错误消失！