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std.datetime.date.DateTime.roll - multiple declarations

Function DateTime.roll

Adds the given number of years or months to this DateTime. A negative number will subtract.

ref DateTime roll(string units) (
  long value,
  AllowDayOverflow allowOverflow = AllowDayOverflow.yes
) pure nothrow @nogc @safe
if (units == "years" || units == "months");

The difference between rolling and adding is that rolling does not affect larger units. Rolling a DateTime 12 months gets the exact same DateTime. However, the days can still be affected due to the differing number of days in each month.

Because there are no units larger than years, there is no difference between adding and rolling years.

Parameters

NameDescription
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, 33, 33);
dt1.roll!"months"(1);
writeln(dt1); // DateTime(2010, 2, 1, 12, 33, 33)

auto dt2 = DateTime(2010, 1, 1, 12, 33, 33);
dt2.roll!"months"(-1);
writeln(dt2); // DateTime(2010, 12, 1, 12, 33, 33)

auto dt3 = DateTime(1999, 1, 29, 12, 33, 33);
dt3.roll!"months"(1);
writeln(dt3); // DateTime(1999, 3, 1, 12, 33, 33)

auto dt4 = DateTime(1999, 1, 29, 12, 33, 33);
dt4.roll!"months"(1, AllowDayOverflow.no);
writeln(dt4); // DateTime(1999, 2, 28, 12, 33, 33)

auto dt5 = DateTime(2000, 2, 29, 12, 30, 33);
dt5.roll!"years"(1);
writeln(dt5); // DateTime(2001, 3, 1, 12, 30, 33)

auto dt6 = DateTime(2000, 2, 29, 12, 30, 33);
dt6.roll!"years"(1, AllowDayOverflow.no);
writeln(dt6); // DateTime(2001, 2, 28, 12, 30, 33)

Function DateTime.roll

Adds the given number of units to this DateTime. A negative number will subtract.

ref DateTime roll(string units) (
  long value
) pure nothrow @nogc @safe
if (units == "days");

ref DateTime roll(string units) (
  long value
) pure nothrow @nogc @safe
if (units == "hours" || units == "minutes" || units == "seconds");

The difference between rolling and adding is that rolling does not affect larger units. For instance, rolling a DateTime one year's worth of days gets the exact same DateTime.

Accepted units are "days", "minutes", "hours", "minutes", and "seconds".

Parameters

NameDescription
units The units to add.
value The number of units to add to this DateTime.

Example

auto dt1 = DateTime(2010, 1, 1, 11, 23, 12);
dt1.roll!"days"(1);
writeln(dt1); // DateTime(2010, 1, 2, 11, 23, 12)
dt1.roll!"days"(365);
writeln(dt1); // DateTime(2010, 1, 26, 11, 23, 12)
dt1.roll!"days"(-32);
writeln(dt1); // DateTime(2010, 1, 25, 11, 23, 12)

auto dt2 = DateTime(2010, 7, 4, 12, 0, 0);
dt2.roll!"hours"(1);
writeln(dt2); // DateTime(2010, 7, 4, 13, 0, 0)

auto dt3 = DateTime(2010, 1, 1, 0, 0, 0);
dt3.roll!"seconds"(-1);
writeln(dt3); // DateTime(2010, 1, 1, 0, 0, 59)

Authors

Jonathan M Davis

License

Boost License 1.0.