/// <summary>
/// Initializes a new instance of <see cref="Age"/>.
/// </summary>
/// <param name="start">The date and time when the age started.</param>
/// <param name="end">The date and time when the age ended.</param>
/// <param name="calendar">Calendar used to calculate age.</param>
public Age(DateTime start, DateTime end, Calendar calendar)
{
if (start > end) throw new ArgumentException("The starting date cannot be later than the end date.");
var startDate = start.Date;
var endDate = end.Date;
_years = _months = _days = 0;
_days += calendar.GetDayOfMonth(endDate) - calendar.GetDayOfMonth(startDate);
if (_days < 0)
{
_days += calendar.GetDaysInMonth(calendar.GetYear(startDate), calendar.GetMonth(startDate));
_months--;
}
_months += calendar.GetMonth(endDate) - calendar.GetMonth(startDate);
if (_months < 0)
{
_months += calendar.GetMonthsInYear(calendar.GetYear(startDate));
_years--;
}
_years += calendar.GetYear(endDate) - calendar.GetYear(startDate);
var ts = endDate.Subtract(startDate);
_totalDays = (Int32)ts.TotalDays;
}