NAME
`Time::timegm' - a UTC version of `mktime()'
SYNOPSIS
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";
DESCRIPTION
The POSIX standard provides three functions for converting between
integer epoch values and 6-component "broken-down" time representations.
`localtime' and `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
`mktime' and `gmtime' functions provided by the system to ensure its
results are always consistent with the other functions.
FUNCTIONS
$epoch = timegm( $sec, $min, $hour, $mday, $mon, $year )
Returns the epoch integer value representing the time given by the 6
broken-down components.
As with `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::Local' also 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 `timegm(3)' or `_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::Local' re-implements
the logic in perl code. `Time::timegm' will fall back to a perl
implementation only if the XS one cannot be used.
AUTHOR
Paul Evans <
[email protected]>
