using System;using System.Collections.Generic;using System.Collections.Specialized;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Net;using System.Net.Sockets;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace GetIPv4Application{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private void btn_getIPv4_Click(object sender, EventArgs e)        {            ShowIP();        }        void ShowIP()        {            richTextBoxIPv4.Text = string.Empty;            //ipv4地址也可能不止一个              foreach (string ip in GetLocalIpv4())            {                this.richTextBoxIPv4.AppendText(ip.ToString()+"\n");            }            return;        }        string[] GetLocalIpv4()        {            //事先不知道ip的个数，数组长度未知，因此用StringCollection储存              IPAddress[] localIPs;            localIPs = Dns.GetHostAddresses(Dns.GetHostName());            StringCollection IpCollection = new StringCollection();            foreach (IPAddress ip in localIPs)            {                //根据AddressFamily判断是否为ipv4,如果是InterNetWorkV6则为ipv6                  if (ip.AddressFamily == AddressFamily.InterNetwork)                    IpCollection.Add(ip.ToString());            }            string[] IpArray = new string[IpCollection.Count];            IpCollection.CopyTo(IpArray, 0);            return IpArray;        }    }}