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这是我的代码Form1：

namespace Irc_Bot
{
    public partial class Form1 : Form
    {
        int port;
        string buf, nick, owner, server, chan;
        System.Net.Sockets.TcpClient sock = new System.Net.Sockets.TcpClient();
        System.IO.TextReader input;
        System.IO.TextWriter output;

        public Form1()
        {
            InitializeComponent();

            //Get nick, owner, server, port, and channel from user
            label1.Text = "Enter bot nick: ";
            nick = textBox1.Text;
            label2.Text = "Enter bot owner name: ";
            owner = textBox2.Text;
            label3.Text = "Enter server name: ";
            label4.Text = "Enter port number: ";
            if (textBox4.Text != "")
            port = Convert.ToInt32(textBox4.Text);
            label5.Text = "Channel: ";
            chan = textBox5.Text;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
        }

        private void connectToIrc()
        {
            //Connect to irc server and get input and output text streams from TcpClient.
            server = textBox3.Text;
            port = Convert.ToInt32(textBox4.Text);
            sock.Connect("chat.eu.freenode.net", port);//server, port);

            if (!sock.Connected)
            {
                Console.WriteLine("Failed to connect!");
                return;
            }

            input = new System.IO.StreamReader(sock.GetStream());
            output = new System.IO.StreamWriter(sock.GetStream());

             //Starting USER and NICK login commands 
         output.Write(
            "USER " + nick + " 0 * :" + owner + "\r\n" +
            "NICK " + nick + "\r\n"
         );

         output.Flush();

         //Process each line received from irc server
         for (buf = input.ReadLine(); ; buf = input.ReadLine())
         {
             //Display received irc message
             Console.WriteLine(buf);

             //Send pong reply to any ping messages
             if (buf.StartsWith("PING ")) { output.Write(buf.Replace("PING", "PONG") + "\r\n"); output.Flush(); }
             if (buf[0] != ':') continue;

             /* IRC commands come in one of these formats:
              * :NICK!USER@HOST COMMAND ARGS ... :DATA\r\n
              * :SERVER COMAND ARGS ... :DATA\r\n
              */

             //After server sends 001 command, we can set mode to bot and join a channel
             if (buf.Split(' ')[1] == "001")
             {
                 output.Write(
                    "MODE " + nick + " +B\r\n" +
                    "JOIN " + chan + "\r\n"
                 );
                 output.Flush();
             }
         }
       }

        private void button1_Click(object sender, EventArgs e)
        {
            connectToIrc();
        }
    }
}

例如，我输入chat.eu.freenode.net服务器名称和端口 6667。

如果我通过 MIRC 程序进入这个服务器，它就可以工作。

但是在我的程序中，在FOR循环中进行了 3-4 次迭代后，我在这一行得到了异常 null：

if (buf.StartsWith("PING "))

变量buf是null。

首先，它会进行几次迭代，然后在执行命令 3-5 次后：continue;然后等待将近 15 秒，然后跳到该行： 

if (buf.StartsWith("PING "))

并抛出异常空消息。

你调用的对象是空的

System.NullReferenceException was unhandled
HResult=-2147467261
Message=Object reference not set to an instance of an object.
Source=Irc Bot

How can solve it ?

4

1 回答 1

5

This part of the code is probably what's causing the error.

for (buf = input.ReadLine(); ; buf = input.ReadLine())

If there's only one line being sent then the first ReadLine takes that line and the second one gets null, resulting in buf being null if only one line is being sent.

Remove one of the buf = input.ReadLine() and also add a check that buf != null before you start to process it. That could look something like this. Notice that you have a buf = input.ReadLine(); both before, and at the end of, the while loop. I've also added an ERROR check in the middle because I encountered an infinite loop on if (buf[0] != ':') continue; when I was testing with some invalid parameters.

//Process each line received from irc server
buf = input.ReadLine();
while (buf != null)
{

  //Display received irc message
  Console.WriteLine(buf);

  if (buf.StartsWith("ERROR")) break;

  //Send pong reply to any ping messages
  if (buf.StartsWith("PING ")) { output.Write(buf.Replace("PING", "PONG") + "\r\n"); output.Flush(); }
  if (buf[0] != ':') continue;

  //After server sends 001 command, we can set mode to bot and join a channel
  if (buf.Split(' ')[1] == "001")
  {
    output.Write(
      "MODE " + nick + " +B\r\n" +
      "JOIN " + chan + "\r\n"
    );
    output.Flush();
  }
  buf = input.ReadLine();
}
于 2013-08-23T06:55:05.947 回答