Re^2: Sort directories by date

It just occurred to me that a GRTish, guaranteed-single-pass solution is possible:

c:\@Work\Perl\monks>perl -wMstrict -le
"use List::Util qw(maxstr);
 ;;
 my @dates = qw(
   12112014
   12012014
   01052015
   12202014
   12022014
   02202015
   03102015
   01012011
   09092015
   04092015
   );
 ;;
 my $most_recent =
   unpack 'x4a*',
   maxstr
   map pack('a4a*', unpack('x4a4', $_), $_),
   @dates
   ;
 ;;
 print $most_recent;
"
09092015
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Use minstr for least-recent date. See the core module List::Util. No efficiency/performance testing done nor claims made. (Update: Actually, I'd be surprised if there's any advantage unless you're dealing with really large lists; default sort (with no subroutine block) is pretty fast!)

Update: See also pack, unpack, perlpacktut.

Give a man a fish: <%-{-{-{-<

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Re^3: Sort directories by date by Laurent_R (Canon) on Sep 29, 2015 at 18:52 UTC
Yes, it is a fairly nice way of doing it.++ I had also been thinking about some similar form of GR-like transform (though I had not thought about using the `maxstr` function of `List::Until`), but I finally preferred to make my algorithmic point with a simple basic straight-forward and manual search of the maximum date. I also agree that the various ways of doing that have little consequence on performance unless the list is really very long.	[reply] [d/l] [select]

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Re^3: Sort directories by date
by Laurent_R (Canon) on Sep 29, 2015 at 18:52 UTC

I had also been thinking about some similar form of GR-like transform (though I had not thought about using the maxstr function of List::Until), but I finally preferred to make my algorithmic point with a simple basic straight-forward and manual search of the maximum date.

I also agree that the various ways of doing that have little consequence on performance unless the list is really very long.

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