How to find last day of month? - dart

Question

I am trying the new Google Dart language and I don't know how to get the last day of the current month?
This gives me current date:
var now = new DateTime.now();

Answer 1

Providing a day value of zero for the next month gives you the previous month's last day
var date = new DateTime(2013,3,0);
print(date.day); // 28 for February

Answer 2

If you want to get the last date of the current month, you need to refer to the 0th day of the next month
Try this in an easy way:
DateTime now = DateTime.now();
int lastday = DateTime(now.year, now.month + 1, 0).day;

Answer 3

Here's one way to find it:
var now = new DateTime.now();
// Find the last day of the month.
var beginningNextMonth = (now.month < 12) ? new DateTime(now.year, now.month + 1, 1) : new DateTime(now.year + 1, 1, 1);
var lastDay = beginningNextMonth.subtract(new Duration(days: 1)).day;
print(lastDay); // 28 for February
I have the current date, so I construct the first day of the next month, and then subtract one day out of it. I'm also taking the change of the year into account.
Update: Here's a little bit shorter code for the same thing, but inspired by Chris's zero-trick:
var now = new DateTime.now();
// Find the last day of the month.
var lastDayDateTime = (now.month < 12) ? new DateTime(now.year, now.month + 1, 0) : new DateTime(now.year + 1, 1, 0);
print(lastDayDateTime.day); // 28 for February
It has the additional check/code, in case you want to do this programmatically (e.g. you have a specific month as an integer).

Answer 4

Here's an extension that might help. (Ref. from Kai's and Chris's answers.)
extension DateTimeExtension on DateTime {
DateTime get firstDayOfWeek => subtract(Duration(days: weekday - 1));
DateTime get lastDayOfWeek =>
add(Duration(days: DateTime.daysPerWeek - weekday));
DateTime get lastDayOfMonth =>
month < 12 ? DateTime(year, month + 1, 0) : DateTime(year + 1, 1, 0);
}

Answer 5

Another way is using Jiffy. It has the endOf method that makes easy to get the last moment of several units, in this case the month:
Jiffy().endOf(Units.MONTH);

Answer 6

While all this answers are correct & do give you the last DAY of the month :
like so : year-month-lastDay 00:00:00.000 -> beginning of the last day of the month
You might need the last bound / DateTime of the month :
like so : year-month-lastDay 23:59:59.999 -> end of the last day of the month
Here is how to get the two bounds within a month with the help of an extension on DateTime :
extension MonthsBounds on DateTime {
DateTime get lastMillisecondOfMonth =>
month < 12 ? DateTime(year, month + 1, 1, 00, 00, 00, -1) : DateTime(year + 1, 1, 1, 00, 00, 00, -1);
DateTime get firstMillisecondOfMonth => DateTime(year, month, 1);
}
print('${DateTime(2022, 12, 14).lastMillisecondOfMonth}'); // 2022-12-31 23:59:59.999

Answer 7

DateTime first = DateTime(month.value.year, month.value.month, 1);
DateTime end = Jiffy(first).add(months: 1, days: -1).dateTime;