C#正则表达式判断是否为IP地址

       public static bool IsIP(string ip)
        {
            //判断是否为IP
            return Regex.IsMatch(ip, @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$");
        }