System.Globalization.GregorianCalendarHelper.TimeToTicks C# (CSharp) Method

        internal static long TimeToTicks(int hour, int minute, int second, int millisecond)
        {
            //TimeSpan.TimeToTicks is a family access function which does no error checking, so
            //we need to put some error checking out here.
            if (hour >= 0 && hour < 24 && minute >= 0 && minute < 60 && second >=0 && second < 60)
            {
                if (millisecond < 0 || millisecond >= MillisPerSecond) {
                    throw new ArgumentOutOfRangeException(
                                "millisecond", 
                                String.Format(
                                    CultureInfo.CurrentCulture,
                                    Environment.GetResourceString("ArgumentOutOfRange_Range"), 
                                    0, 
                                    MillisPerSecond - 1));
                }                    
                return (TimeSpan.TimeToTicks(hour, minute, second) + millisecond * TicksPerMillisecond);;
            }
            throw new ArgumentOutOfRangeException(null, Environment.GetResourceString("ArgumentOutOfRange_BadHourMinuteSecond"));
        }
        

        public DateTime ToDateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int era)
        {
            year = this.GetGregorianYear(year, era);
            long ticks = GregorianCalendarHelper.DateToTicks(year, month, day) + GregorianCalendarHelper.TimeToTicks(hour, minute, second, millisecond);

            this.CheckTicksRange(ticks);
            return(new DateTime(ticks));
        }