提示未将对象引用设置到对象的实例

Question

 public void login()
     {       clientSocket = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
       IPEndPoint ep = new IPEndPoint(Dns.GetHostEntry(remoteHost).AddressList[0], remotePort);       try
       {
         clientSocket.Connect(ep);
       }
       catch(Exception)
       {
         throw new IOException("Couldn't connect to remote server");
       }       readReply();
       if(retValue != 220)
       {
         close();
         throw new IOException(reply.Substring(4));
       }
       if(debug)
         //Console.WriteLine("USER "+remoteUser);       sendCommand("USER "+remoteUser);       if( !(retValue == 331 || retValue == 230) )
       {
         cleanup();
         //throw new IOException(reply.Substring(4));
       }       if( retValue != 230 )
       {
         if(debug)
          //Console.WriteLine("PASS xxx");         sendCommand("PASS "+remotePass);
         if( !(retValue == 230 || retValue == 202) )
         {
           cleanup();
           //throw new IOException(reply.Substring(4));
         }
       }       logined = true;
       //Console.WriteLine("Connected to "+remoteHost);       chdir(remotePath);     }     ///
     /// Close the FTP connection.
     ///
     public void close()
     {         if (clientSocket != null)
         {
             sendCommand("QUIT");
         }         cleanup();
         //Console.WriteLine("Closing...");
     }
     #endregion     #region 设置FTP文件读取模式
     /// <summary>
     /// 设置FTP文件读取模式(二进制、文本)
     /// </summary>
     /// <param name="mode">文件读取模式(二进制(True)、文本(False))</param>
     public void setBinaryMode(Boolean mode)
     {
       if(mode)
       {
         sendCommand("TYPE I");
       }
       else
       {
         sendCommand("TYPE A");
       }
       if (retValue != 200)
       {
         throw new IOException(reply.Substring(4));
       }
     } private void sendCommand(String command)
     {
        
       Byte[] cmdBytes = 
        GetEncoding().GetBytes((command+"\r\n").ToCharArray());
       clientSocket.Send(cmdBytes, cmdBytes.Length, 0);
       readReply();     }运行到clientSocket.Send(cmdBytes, cmdBytes.Length, 0); 
提示未将对象引用设置到对象的实例  怎么回事呢

Answer 1

看看cmdBytes这个数组  为空了

Answer 2

cleanup()是怎么写的？是不是把socket给dispose了

Answer 3

  criedshy  正解 socket dispose了在登陆时
  
   if( !(retValue == 331 || retValue == 230) )
       {
         cleanup();
         throw new IOException(reply.Substring(4));
       }
在登陆时retValue等示220
throw new IOException(reply.Substring(4));
这个提示
Serv-U FTP Server v6.4 for WinSock ready...这又是怎么回来呢