- 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.
$epoch = timegm( $sec, $min, $hour, $mday, $mon, $year )
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.
COMPARISON WITH Time::Local
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>