using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace IPFlag{    public class Class1    {        public bool ISIP(string ip)        {            bool b = true;            string[] lines = new string[4];            string s = ".";            lines = ip.Split(s.ToCharArray(), 4);//分隔字符串            try            {                for (int i = 0; i < 4; i++)                {                    if (Convert.ToInt32(lines[i]) >= 255 || Convert.ToInt32(lines[i]) < 0)                    {                        b = false;                        return b;                    }                }                return b;            }            catch { return false; }        }    }}