LPM: The times they are a-changin' (or: integer hash keys)

[David Hempy]

Well, since Y2K was such a fizzle, we get another chance at notoriety on 
September 8, 2001, when we exceed 999,999,999 seconds since the 
epoch.  Shouldn't be a big deal, as that's only one less than 1,000,000,000 
seconds.

But yet, I'm facing it in one of my programs...

I got a call from a user complaining that September 8th's program schedule 
was out of order.  Everything after 9:30 PM (EDT) showed up first, before 
our first show at 8:00 AM.  Sure enough, she was right:

http://edit-www.ket.org/cgi-plex/schedule/ribbon_funnytime.pl?date=2001-09-08


It didn't take too long to figure notice the coincidence between the 
sorting problem and the 9+1 issue.  After convincing myself that SQL Server 
didn't know how to sort these values correctly (duh) I looked at my own code.

Turns out the problem was actually me not understanding how hash keys 
work.  I was using epoch times as hash keys.  It appears that hash keys are 
stored as strings, not the integers I was expecting.  For example:

$foo{1} = "one";
$foo{2} = "two";
$foo{3} = "three";
$foo{10} = "ten";
$foo{20} = "twenty";
$foo{30} = "thirty";

foreach my $key (sort keys %foo) {
	print "$key - $foo{$key}\n";
}
	

This produces this output:
1 - one
10 - ten
2 - two
20 - twenty
3 - three
30 - thirty


Any suggestions on a good way to sort hash keys by their integer values?


-dave

-- 
David Hempy
Internet Database Administrator
Kentucky Educational Television - Distance Learning Division
<hempy at ket.org> -- (859)258-7164 -- (800)333-9764