- COMPARISON WITH Time::Local
Time::timegm - a UTC version of
use Time::timegm qw( timegm ); my $epoch = timegm( 0, 0, 0, 14, 6-1, 2012-1900 ); print "2012-06-14 00:00:00 UTC happened at ", scalar localtime($epoch), " localtime\n";
The POSIX standard provides three functions for converting between integer epoch values and 6-component "broken-down" time representations.
gmtime convert an epoch into the 6 components of seconds, minutes, hours, day of month, month and year, in either local timezone or UTC. The
mktime function converts a local broken-down time into an epoch value. However,
POSIX does not provide a UTC version of this.
This module provides a function
timegm which has this ability.
Unlike some other CPAN implementations of this behaviour, this version does not re-implement the time handling logic internally. It reuses the
gmtime functions provided by the system to ensure its results are always consistent with the other functions.
Returns the epoch integer value representing the time given by the 6 broken-down components.
POSIX::mktime it is not required that these values be within their "valid" ranges. This function will normalise values out of range. For example, the 25th hour of a day is normalised to the 1st hour of the following day; or the 0th month is normalised to the 12th month of the preceeding year.
The Time::Local module also provides a function called
timegm() with similar behaviour to this one. The differences are:
Time::timegm::timegm()handles denormalised values (that is, seconds or minutes outside of the range 0 to 59, hours outside 0 to 23, etc..) by adjusting the next largest unit (such that 61 seconds is 1 second of the next minute, etc).
Time::Local::timegm()croaks on out-of-range input.
Time::Localalso provides a function
timegm_nocheck()which does not croak but it is documented that the behavior is unspecified on out-of-range values.
Time::timegm::timegm()is implemented by a light XS wrapper around the
_mkgmtime(3)function provided by the platform's C library if such a function is provided, so its behaviour is consistent with the rest of the platform.
Time::Localre-implements the logic in perl code.
Time::timegmwill fall back to a perl implementation only if the XS one cannot be used.
Paul Evans <email@example.com>