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Function std.datetime.DateTime.add
Adds the given number of years or months to this DateTime. A
negative number will subtract.
Note that if day overflow is allowed, and the date with the adjusted
year/month overflows the number of days in the new month, then the month
will be incremented by one, and the day set to the number of days
overflowed. (e.g. if the day were 31 and the new month were June, then
the month would be incremented to July, and the new day would be 1). If
day overflow is not allowed, then the day will be set to the last valid
day in the month (e.g. June 31st would become June 30th).
Prototype
ref DateTime add(string units)( long value, AllowDayOverflow allowOverflow = AllowDayOverflow.yes ) pure nothrow @safe if (units == "years" || units == "months");
Parameters
| Name | Description |
|---|---|
| units | The type of units to add ("years" or "months"). |
| value | The number of months or years to add to this
DateTime. |
| allowOverflow | Whether the days should be allowed to overflow,
causing the month to increment. |
Example
auto dt1 = DateTime(2010, 1, 1, 12, 30, 33); dt1.add!"months"(11); assert(dt1 == DateTime(2010, 12, 1, 12, 30, 33)); auto dt2 = DateTime(2010, 1, 1, 12, 30, 33); dt2.add!"months"(-11); assert(dt2 == DateTime(2009, 2, 1, 12, 30, 33)); auto dt3 = DateTime(2000, 2, 29, 12, 30, 33); dt3.add!"years"(1); assert(dt3 == DateTime(2001, 3, 1, 12, 30, 33)); auto dt4 = DateTime(2000, 2, 29, 12, 30, 33); dt4.add!"years"(1, AllowDayOverflow.no); assert(dt4 == DateTime(2001, 2, 28, 12, 30, 33));
Authors
Jonathan M Davis and Kato Shoichi