/// <summary>
        /// DateDiff in SQL style.
        /// Datepart implemented:
        ///     "year" (abbr. "yy", "yyyy"),
        ///     "quarter" (abbr. "qq", "q"),
        ///     "month" (abbr. "mm", "m"),
        ///     "day" (abbr. "dd", "d"),
        ///     "week" (abbr. "wk", "ww"),
        ///     "hour" (abbr. "hh"),
        ///     "minute" (abbr. "mi", "n"),
        ///     "second" (abbr. "ss", "s"),
        ///     "millisecond" (abbr. "ms").
        /// </summary>
        /// <param name="startDate"></param>
        /// <param name="datePart"></param>
        /// <param name="endDate"></param>
        /// <returns></returns>
        public static Int64 DateDiff(this DateTime startDate, String datePart, DateTime endDate)
        {
            Int64 dateDiffVal;
            System.Globalization.Calendar cal = System.Threading.Thread.CurrentThread.CurrentCulture.Calendar;
            TimeSpan ts = new TimeSpan(endDate.Ticks - startDate.Ticks);
            switch (datePart.ToLower().Trim())
            {
                #region year

                case "year":
                case "yy":
                case "yyyy":
                    dateDiffVal = cal.GetYear(endDate) - cal.GetYear(startDate);
                    break;

                #endregion

                #region quarter

                case "quarter":
                case "qq":
                case "q":
                    dateDiffVal = (((cal.GetYear(endDate) - cal.GetYear(startDate)) * 4) + ((cal.GetMonth(endDate) - 1) / 3)) - ((cal.GetMonth(startDate) - 1) / 3);
                    break;

                #endregion

                #region month

                case "month":
                case "mm":
                case "m":
                    dateDiffVal = ((cal.GetYear(endDate) - cal.GetYear(startDate)) * 12 + cal.GetMonth(endDate)) - cal.GetMonth(startDate);
                    break;

                #endregion

                #region day

                case "day":
                case "d":
                case "dd":
                    dateDiffVal = (Int64)ts.TotalDays;
                    break;

                #endregion

                #region week

                case "week":
                case "wk":
                case "ww":
                    dateDiffVal = (Int64)(ts.TotalDays / 7);
                    break;

                #endregion

                #region hour

                case "hour":
                case "hh":
                    dateDiffVal = (Int64)ts.TotalHours;
                    break;

                #endregion

                #region minute

                case "minute":
                case "mi":
                case "n":
                    dateDiffVal = (Int64)ts.TotalMinutes;
                    break;

                #endregion

                #region second

                case "second":
                case "ss":
                case "s":
                    dateDiffVal = (Int64)ts.TotalSeconds;
                    break;

                #endregion

                #region millisecond

                case "millisecond":
                case "ms":
                    dateDiffVal = (Int64)ts.TotalMilliseconds;
                    break;

                #endregion

                default:
                    throw new Exception(String.Format("DatePart \"{0}\" is unknown", datePart));
            }
            return dateDiffVal;
        }

/// <summary>
        /// بررسی اینکه رشته وارد شده با قالب مورد نظر مطابقت دارد یا خیر
        /// </summary>
        /// <param name="source">متن وارد شده</param>
        /// <param name="regexTemplate">قالب مورد نظر</param>
        /// <returns></returns>
        public static Boolean IsMatchTemplate(this String source, String regexTemplate)
        {
            var regex = new Regex(regexTemplate);
            return regex.IsMatch(source);
        }