正则表达式 判断IP 数字

            public static bool checkIP(string strIP)
            {
                //string regex = @"^(2[0-4]\d | 25[0-5] | [01]?\d?[1-9])\." +
                //                @"(2[0-4]\d | 25[0-5] | [01]?\d?\d)\." +
                //                @"(2[0-4]\d | 25[0-5] | [01]?\d?\d)\." +
                //                @"(2[0-4]\d | 25[0-5] | [01]?\d?\d)$";
                String regex = "^(1\\d{2}|2[0-4]\\d|25[0-5]|[1-9]\\d|[1-9])\\."
                                + "(1\\d{2}|2[0-4]\\d|25[0-5]|[1-9]\\d|\\d)\\."
                                + "(1\\d{2}|2[0-4]\\d|25[0-5]|[1-9]\\d|\\d)\\."
                                + "(1\\d{2}|2[0-4]\\d|25[0-5]|[1-9]\\d|\\d)$";
                if (System.Text.RegularExpressions.Regex.IsMatch(strIP, regex))
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }


            public static bool checkNumber(string strText)
            {
                String regex = "^[1-9]\\d*$"; //匹配数字并且不以0开头
                // String regex = "^[0-9]*$";  //匹配数字 
                if (System.Text.RegularExpressions.Regex.IsMatch(strText, regex))
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }

            public static bool checkNumOut(string strNum)
            {
                //String regex = @"^[\d,]+$" ; 
                String regex = @"^[\d][\,\d]*$"; //匹配数字，逗号
                if (System.Text.RegularExpressions.Regex.IsMatch(strNum, regex))
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }

            public static void checkIP(TextBox txt, string mes)
            {
                if (txt.Text.Trim() != "" && !Global.Methods.checkIP(txt.Text.Trim()))
                {
                    txt.Text = "";
                    txt.Focus();
                    if (mes == "")
                        MessageBox.Show("IP地址不合法", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    else
                        MessageBox.Show(mes + "不合法", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);

                }
            }

  /// <summary>
        /// 验证字符串是否 匹配数字、字母、汉字
        /// </summary>
        /// <param name="isNumber">匹配数字还是匹配数字、字母、汉字</param>
        /// <param name="str">输入的字符串</param>
        /// <param name="IsReturn">是否需要返回忽略特殊字符的字符串</param>
        /// <returns></returns>
        private bool checkFormat(bool IsNumber, ref string str, bool IsReturn)
        {
            bool result = false;
            string regex = "^[0-9]*$";  //匹配数字 
            if (!IsNumber) regex = @"^[\w ]+$"; //匹配数字、字母、汉字
            var reg = new System.Text.RegularExpressions.Regex(regex);// 
            //var str = this.Text.Replace(" ", "");
            var sb = new StringBuilder();
            if (reg.IsMatch(str))
            {
                result = true;
            }
            else
            {
                if (IsReturn)
                {
                    for (int i = 0; i < str.Length; i++)
                    {
                        if (reg.IsMatch(str[i].ToString()))
                        {
                            sb.Append(str[i].ToString());
                        }
                    }
                    str = sb.ToString();
                }
            }
            return result;
        }