Detailed explanation of the code case for obtaining the local IP address (ipv4) in C#

This article mainly introduces the method of C# to obtain all IP addresses of this machine, the method of C# to obtain the IP address of this machine (ipv4), etc. Has very good reference value. Let’s take a look with the editor below

Get all the IP addresses of this machine:

These addresses are the ipv4 and ipv6 addresses that include all network cards (virtual network cards).

 string name = Dns.GetHostName(); 
 IPAddress[] ipadrlist = Dns.GetHostAddresses(name);

Get all IPV4 addresses of this machine:

string name = Dns.GetHostName(); 
IPAddress[] ipadrlist = Dns.GetHostAddresses(name); 
foreach (IPAddress ipa in ipadrlist) 
{ 
  if (ipa.AddressFamily == AddressFamily.InterNetwork) 
  Console.Writeline(ipa.ToString()); 
}

To get the ipv4 address alone, you can use IPAdress.AddressFamily AttributesJudgement: For IPv4 , returns InterNetwork; for IPv6, returns InterNetworkV6.

However, if this machine may have multiple ipv4 addresses, how to obtain the network card IP used when accessing the default gateway. I found the master's method on the CSDN forum, using the querylocalrouting table.

Get the ipv4 address being used by this machine (the IP used to access the Internet)

Don’t underestimate it, there are still many things to consider:

1. A computer has multiple network cards, wired, wireless, and vmare virtual network cards.

2. Even if there is only one network card, the network card is configured with N IP addresses, including ipv6 addresses.

/// <summary> 
 /// 获取当前使用的IP 
 /// </summary> 
 /// <returns></returns> 
 public static string GetLocalIP() 
 { 
 string result = RunApp("route", "print",true); 
 Match m = Regex.Match(result, @"0.0.0.0\s+0.0.0.0\s+(\d+.\d+.\d+.\d+)\s+(\d+.\d+.\d+.\d+)"); 
 if (m.Success) 
 { 
  return m.Groups[2].Value; 
 } 
 else 
 { 
  try 
  { 
  System.Net.Sockets.TcpClient c = new System.Net.Sockets.TcpClient(); 
  c.Connect("www.baidu.com", 80); 
  string ip = ((System.Net.IPEndPoint)c.Client.LocalEndPoint).Address.ToString(); 
  c.Close(); 
  return ip; 
  } 
  catch (Exception) 
  { 
  return null; 
  } 
 } 
 } 
 /// <summary> 
 /// 获取本机主DNS 
 /// </summary> 
 /// <returns></returns> 
 public static string GetPrimaryDNS() 
 { 
 string result = RunApp("nslookup", "",true); 
 Match m = Regex.Match(result, @"\d+\.\d+\.\d+\.\d+"); 
 if (m.Success) 
 { 
  return m.Value; 
 } 
 else 
 { 
  return null; 
 } 
 } 
 /// <summary> 
 /// 运行一个控制台程序并返回其输出参数。 
 /// </summary> 
 /// <param name="filename">程序名</param> 
 /// <param name="arguments">输入参数</param> 
 /// <returns></returns> 
 public static string RunApp(string filename, string arguments,bool recordLog) 
 { 
 try 
 { 
  if (recordLog) 
  { 
  Trace.WriteLine(filename + " " + arguments); 
  } 
  Process proc = new Process(); 
  proc.StartInfo.FileName = filename; 
  proc.StartInfo.CreateNoWindow = true; 
  proc.StartInfo.Arguments = arguments; 
  proc.StartInfo.RedirectStandardOutput = true; 
  proc.StartInfo.UseShellExecute = false; 
  proc.Start(); 
  using (System.IO.StreamReader sr = new System.IO.StreamReader(proc.StandardOutput.BaseStream, Encoding.Default)) 
  { 
  //string txt = sr.ReadToEnd(); 
  //sr.Close(); 
  //if (recordLog) 
  //{ 
  // Trace.WriteLine(txt); 
  //} 
  //if (!proc.HasExited) 
  //{ 
  // proc.Kill(); 
  //} 
  //上面标记的是原文，下面是我自己调试错误后自行修改的 
  Thread.Sleep(100);  //貌似调用系统的nslookup还未返回数据或者数据未编码完成，程序就已经跳过直接执行 
      //txt = sr.ReadToEnd()了，导致返回的数据为空，故睡眠令硬件反应 
  if (!proc.HasExited)  //在无参数调用nslookup后，可以继续输入命令继续操作，如果进程未停止就直接执行 
  {    //txt = sr.ReadToEnd()程序就在等待输入，而且又无法输入，直接掐住无法继续运行 
   proc.Kill(); 
  } 
  string txt = sr.ReadToEnd(); 
  sr.Close(); 
  if (recordLog) 
   Trace.WriteLine(txt); 
  return txt; 
  } 
 } 
 catch (Exception ex) 
 { 
  Trace.WriteLine(ex); 
  return ex.Message; 
 } 
 }

There is another way to get it by using ipconfig:

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

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