原型：int PASCAL FAR WSAStartup(WORD wVersionRequested, LPWSADATA lpWSAData );

[DllImport("ws2_32.dll")]

public static extern Int32 WSAStartup(UInt16 wVer, ref WSADATA wsaData);

public struct WSADATA //這樣宣告結構體

{

public short wVersion;

public short wHighVersion;

[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 6)]

public string szDescription;

[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 6)]

public string szSystemStatus;

[Obsolete]

public int wMaxSockets;

[Obsolete]

public int wMAXUDPDG;

public IntPtr dwVendorInfo;

}

例項化結構體：

WSADATA wsaData = new WSADATA();

WSAStartup(0x0202, ref wsaData); //注意第二個引數前的ref ,0x202指Socket的版本號