string strIp = "0.0.0.0         0.255.255.255   IANA保留地址  CZ88.NET";

            //刚接触正则，想分为3组 写的有点问题 帮忙修改下 谢谢了
            Regex reg = new Regex(@"(.+\s+)(.+\s+)(.+\s.+)");
            Match mat = reg.Match(strIp);
            if (mat.Success)
            {
                string str1 = mat.Groups[1].Value;
                string str2 = mat.Groups[2].Value;
                string str3 = mat.Groups[3].Value;
            }

static void Main(string[] args)
            {

                string strIp = "0.0.0.0         0.255.255.255   IANA保留地址  CZ88.NET";
                Regex reg = new Regex(@"([^\s]+)\s*([^\s]+)\s*(.*)", RegexOptions.None);
                Match mat = reg.Match(strIp);
                if (mat.Success)
                {
                    string str1 = mat.Groups[1].Value;
                    string str2 = mat.Groups[2].Value;
                    string str3 = mat.Groups[3].Value;
                    Console.WriteLine(str1);
                    Console.WriteLine(str2);
                    Console.WriteLine(str3);
                }


            

                Console.ReadLine();
                                              
            }

------解决方案--------------------

C# code

 string strIp = "0.0.0.0         0.255.255.255   IANA保留地址  CZ88.NET";

            //刚接触正则，想分为3组 写的有点问题 帮忙修改下 谢谢了
            Regex reg = new Regex(@"([\d.]*)\s*([\d.]*)\s*(.*)");
            Match mat = reg.Match(strIp);
            if (mat.Success)
            {
                string str1 = mat.Groups[1].Value;
                string str2 = mat.Groups[2].Value;
                string str3 = mat.Groups[3].Value;
            }