小妹请教关于DLL函数的小问题

Question

null 和 0 好象都不行
但在 vc 里就用 null

Answer 1

// 溢出缓冲区 overlapped buffer
[StructLayout(LayoutKind.Sequential)]
private struct OVERLAPPED { 
    public int  Internal; 
    public int  InternalHigh; 
    public int  Offset; 
    public int  OffsetHigh; 
    public int hEvent; 
} [DllImport("kernel32.dll", SetLastError=true)]
 static extern int WaitCommEvent (
     int hFile, 
     ref int lpEvtMask, 
     ref OVERLAPPED lpOverlapped) 这样就可以了。

Answer 2

// 溢出缓冲区 overlapped buffer
[StructLayout(LayoutKind.Sequential)]
private class OVERLAPPED {    //change struct to class
    public int  Internal; 
    public int  InternalHigh; 
    public int  Offset; 
    public int  OffsetHigh; 
    public int hEvent; 
} [DllImport("kernel32.dll", SetLastError=true)]
 static extern int WaitCommEvent (
     int hFile, 
     ref int lpEvtMask, 
     OVERLAPPED lpOverlapped);    //remove refNow you can use null.