Date Time

DateTime Extensions

StartOf & EndOf

Provides operations for the DateTime / DateTimeOffset to return time to a starting point or advance to an end point.

There are the StartOf functions:

Name	Example	Result
StartOfYear	(2020, 11, 13, 20, 30, 1) .StartOfYear()	2020/1/1 0:00:00:000
StartOfMonth	(2020, 11, 13, 20, 30, 1) .StartOfMonth()	2020/11/1 0:00:00:000
StartOfDay	(2020, 11, 13, 20, 30, 1) .StartOfDay()	2020/11/13 0:00:00:000
StartOfHour	(2020, 11, 13, 20, 30, 1) .StartOfHour()	2020/11/13 20:00:00:000
StartOfMinute	(2020, 11, 13, 20, 30, 1) .StartOfMinute()	2020/11/13 20:30:00:000
StartOfSecond	(2020, 11, 13, 20, 30, 1) .StartOfSecond()	2020/11/13 20:30:01:000

There are the EndOf functions:

Name	Example	Result
EndOfYear	(2020, 11, 13, 20, 30, 1) .EndOfYear()	2020/12/31 23:59:59:999
EndOfMonth	(2020, 11, 13, 20, 30, 1) .EndOfMonth()	2020/11/30 23:59:59:999
EndOfDay	(2020, 11, 13, 20, 30, 1) .EndOfDay()	2020/11/13 23:59:59:999
EndOfHour	(2020, 11, 13, 20, 30, 1) .EndOfHour()	2020/11/13 20:59:59:999
EndOfMinute	(2020, 11, 13, 20, 30, 1) .EndOfMinute()	2020/11/13 20:30:59:999
EndOfSecond	(2020, 11, 13, 20, 30, 1) .EndOfSecond()	2020/11/13 20:30:01:999

Week

Gets the number of weeks in a year for the specified date.

/*  2020 - 01
 *  Su  Mo  Tu  We  Th  Fr  Sa
 *[            ( 1)  2   3   4 ]
 *[( 5)  6   7   8   9  10  11 ]
 *  12  13  14  15  16  17  18
 *  19  20  21  22  23  24  25
 *  26  27  28  29  30  31
 */

Example	Result
(2020, 1, 1) .Week()	0
(2020, 1, 5) .Week()	1

WeekInMonth

Gets the number of weeks in a month for the specified date.

/*  2012 - 04                              2012 - 04
 *  Su  Mo  Tu  We  Th   Fr  Sa            Su  Mo  Tu  We  Th  Fr  Sa
 *                      [     1          [                          1]
 *   2   3   4   5   6] [ 7   8          [  2   3   4   5   6   7   8]
 *   9  10  11  12  13] [14  15          [  9  10  11  12  13  14  15]
 * (16) 17  18  19  20] [21  22          [(16) 17  18  19  20  21  22]
 *  23  24  25  26  27   28  29            23  24  25  26  27  28  29
 *  30                                    30
 */

Example	Result
(2012, 4, 16) .WeekInMonth ( DayOfWeek.Friday )	2
(2012, 4, 16) .WeekInMonth ( DayOfWeek.Sunday )	3

AddDays

Provides a special arithmetic method for calculating working days or non-working days.

public static DateTime AddDays(this DateTime @this, int value, DayMode mode)

public enum DayMode {
    Undefined,
    Weekday,
    Weekend,
}

/*  2020 - 12                             2020 - 12
 *  Su  Mo  Tu  We  Th  Fr  Sa            Su  Mo  Tu  We  Th  Fr  Sa
 *           1   2   3   4   5
 *   6   7   8   9  10  11  12
 * (13) 14  15  16  17  18 [19]
 *  20 [21] 22  23  24  25  26
 *  27  28  29  30  31
 */

Example	Result
(2020, 12, 13) .AddDays ( 6, DayMode.Weekday )	(2020, 12, 21)
(2020, 12, 13) .AddDays ( 1, DayMode.Weekend )	(2020, 12, 19)

AddTotalYears & AddTotalMonths

• AddTotalYears : Returns a new DateTime that adds the specified diff-number of years to the value of this instance.
• AddTotalMonths : Returns a new DateTime that adds the specified diff-number of months to the value of this instance.

Example	Result
(2000, 2, 29) .AddTotalYears ( 1 )	(2001, 3, 1)
(2001, 3, 1) .AddTotalYears ( -1 )	(2000, 3, 1)

Elapsed...

Gets the number of ... elapsed from DateTime.MinValue.

Example	Result
(2012, 4, 16) .ElapsedDays ( )	734608
(2012, 4, 16) .ElapsedMonths ( )	24135.5