判断地址为IPV4的正则表达式

以下是正则表达式：

        #region //IPV4正则表达式函数
        public static bool IsIPv4Address(string ip)
        {
            string pattern = @"^(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]

|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]

|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])$";
            Regex r = new Regex(pattern);
            Match m = r.Match(ip);
            return m.Success;
        }
        #endregion

 使用方法：

IPHostEntry IpEntry = Dns.GetHostEntry(Dns.GetHostName());

                for (int i = 0; i != IpEntry.AddressList.Length; i++)
                {
                    if (IsIPv4Address(IpEntry.AddressList[i].ToString()))
                    {
                       comboBox1.Items.Add(IpEntry.AddressList[i]);
                    }
                }