正则表达式验证字符串是否为IP

  /// <summary>
        /// 验证字符串是否IP合法
        /// </summary>
        /// <returns>是IP返回true 负责返回false</returns>
        private bool IsIP(string ip)
        {
            if (cmbIP.Text.Trim() == ".")
            {
                return true;
            }
            else
            {
                return Regex.IsMatch(ip.Trim(), @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$");
            }
        }