byte[] byData = new byte[100];
        char[] charData = new char[1000];
        public void Read()
        {
            try
            {
                FileStream file = new FileStream("E:\\test.txt", FileMode.Open);
                file.Seek(0, SeekOrigin.Begin);
                file.Read(byData, 0, 100); //byData传进来的字节数组,用以接受FileStream对象中的数据,第2个参数是字节数组中开始写入数据的位置,它通常是0,表示从数组的开端文件中向数组写数据,最后一个参数规定从文件读多少字符.
                Decoder d = Encoding.Default.GetDecoder();
                d.GetChars(byData, 0, byData.Length, charData, 0);
                Console.WriteLine(charData);
                file.Close();
            }
            catch (IOException e)
            {
                Console.WriteLine(e.ToString());
            }
        }
    

    public void Read(string path)
        {
            StreamReader sr = new StreamReader(path,Encoding.Default);
            String line;
            while ((line = sr.ReadLine()) != null) 
            {
                Console.WriteLine(line.ToString());
            }
        }

        public void Write()
        {
            FileStream fs = new FileStream("E:\\ak.txt", FileMode.Create);
            //获得字节数组
            byte[] data = System.Text.Encoding.Default.GetBytes("Hello World!"); 
            //开始写入
            fs.Write(data, 0, data.Length);
            //清空缓冲区、关闭流
            fs.Flush();
            fs.Close();
        }

        public void Write(string path)
        {
            FileStream fs = new FileStream(path, FileMode.Create);
            StreamWriter sw = new StreamWriter(fs);
            //开始写入
            sw.Write("Hello World!!!!");
            //清空缓冲区
            sw.Flush();
            //关闭流
            sw.Close();
            fs.Close();
        }

 1 private void GetIP()  
 2 {  
 3     string hostName = Dns.GetHostName();//本机名   
 4     //System.Net.IPAddress[] addressList = Dns.GetHostByName(hostName).AddressList;//会警告GetHostByName()已过期，我运行时且只返回了一个IPv4的地址   
 5     System.Net.IPAddress[] addressList = Dns.GetHostAddresses(hostName);//会返回所有地址，包括IPv4和IPv6   
 6     foreach (IPAddress ip in addressList)  
 7     {  
 8         listBox1.Items.Add(ip.ToString());  
 9     }  
10 }  

1         static string GetLocalIp()  
2         {  
3             string hostname = Dns.GetHostName();//得到本机名   
4             //IPHostEntry localhost = Dns.GetHostByName(hostname);//方法已过期，只得到IPv4的地址   
5 <SPAN style="WHITE-SPACE: pre"> </SPAN>    IPHostEntry localhost = Dns.GetHostEntry(hostname);  
6             IPAddress localaddr = localhost.AddressList[0];  
7             return localaddr.ToString();  
8         }  

 1        string strUrl = "提供IP查询的网站的链接";  
 2        Uri uri = new Uri(strUrl);  
 3        WebRequest webreq = WebRequest.Create(uri);  
 4        Stream s = webreq .GetResponse().GetResponseStream();  
 5        StreamReader sr = new StreamReader(s, Encoding.Default);  
 6        string all = sr.ReadToEnd();   
 7        int i = all.IndexOf("[") + 1;  
 8        //分析字符串得到IP   
 9        return ip;  
10        /* 
11         我用的是http://www.ip.cn/getip.php?action=getip&ip_url=&from=web    
12         (这种链接很容易找的，百度“IP”得到一些网站，分析一下网站的链接就能得到) 
13         返回的数据是：  
14         <div class="well"><p>当前 IP：<code>0.0.0.0</code>&nbsp;来自：XX省XX市 电信</p><p>GeoIP: Beijing, China</p></div>  
15         解析这段就行  
16       */  

 1    private void GetIP6()  
 2    {  
 3        Process cmd = new Process();  
 4        cmd.StartInfo.FileName = "ipconfig.exe";//设置程序名   
 5        cmd.StartInfo.Arguments = "/all";  //参数   
 6 //重定向标准输出   
 7        cmd.StartInfo.RedirectStandardOutput = true;  
 8        cmd.StartInfo.RedirectStandardInput = true;  
 9        cmd.StartInfo.UseShellExecute = false;  
10        cmd.StartInfo.CreateNoWindow = true;//不显示窗口（控制台程序是黑屏）   
11 //cmd.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;//暂时不明白什么意思   
12        /* 
13 收集一下 有备无患 
14        关于:ProcessWindowStyle.Hidden隐藏后如何再显示？ 
15        hwndWin32Host = Win32Native.FindWindow(null, win32Exinfo.windowsName); 
16        Win32Native.ShowWindow(hwndWin32Host, 1);     //先FindWindow找到窗口后再ShowWindow 
17        */  
18        cmd.Start();  
19        string info = cmd.StandardOutput.ReadToEnd();  
20        cmd.WaitForExit();  
21        cmd.Close();  
22        textBox1.AppendText(info);  
23    }