How do I get yesterday's date using localtime?

Question

How do I tweak this to get yesterday's date using localtime?

use strict;

sub spGetCurrentDateTime;
print spGetCurrentDateTime;

sub spGetCurrentDateTime {
my ($sec, $min, $hour, $mday, $mon, $year) = localtime();
my @abbr = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
my $currentDateTime = sprintf "%s %02d %4d", $abbr[$mon], $mday, $year+1900; #Returns => 'Aug 17 2010' 
return $currentDateTime;
}

~

Answer 1

use DateTime qw();
DateTime->now->subtract(days => 1); 

The expression on the second line returns a DateTime object.

Answer 2

Solution suggested by most users is wrong!

localtime(time() - 24*60*60)

The worst thing you can do is to assume that 1 day = 86400 seconds.

Example: Timezone is America/New_York, date is Mon Apr 3 00:30:00 2006

timelocal gives us 1144038600

localtime(1144038600 - 86400) = Sat Apr 1 23:30:00 EST 2006

oops!

The right and the only solution is to let system function normalize values

$prev_day = timelocal(0, 0, 0, $mday-1, $mon, $year);

Or let datetime frameworks (DateTime, Class::Date, etc) do the same.

That's it.