This appears to work: 

#!/usr/bin/perl
use warnings;
use strict;


my @headers;

while ( <DATA> ) {
    if ( $. == 1 ) {
        print;
        @headers = split;
        next;
        }

    chomp;
    my %data;
    @data{ @headers } = split /\s*~\s*/;

    for ( @data{ @headers[ 1 .. $#headers ] } ) {
        my ( $mon, $day, $year, $hour, $min, $sec ) = /\d\d/g;
        $hour += 12 if /PM/i;
        $_ = join '', $year, $mon, $day, $hour, $min, $sec;
        }

    my $new_order = 1;
    my %ordered = (
        @headers[ 0, 0 ],
        map {
            $headers[ $_ ], $new_order++
            }
        sort {
            $data{ $headers[ $a ] } <=> $data{ $headers[ $b ] }
            }
        1 .. $#headers
        );

    printf "%-7s %-7s %-7s %-7s %-7s\n", @ordered{ @headers };
    }


__DATA__
EVENT   JIM     BOB     SAM     JACK
PTRED~09/29/10 03:23:05 PM ~09/28/10 02:21:09 PM ~09/26/10 11:00:03 AM
+ ~09/27/10 09:33:41 PM
RED~08/29/10 01:55:00 AM ~08/30/09 12:10:10 PM ~08/27/10 08:16:21 PM ~
+09/01/10 12:12:12 AM
INT~07/04/10 03:21:15 AM ~07/08/10 04:17:33 PM ~06/30/10 04:22:11 AM ~
+06/28/10 10:11:01 PM
PTRED~06/19/10 09:19:55 PM ~04/25/10 07:39:22 PM ~09/16/10 10:34:24 AM
+ ~07/22/10 06:19:38 PM
RED~04/29/10 12:10:59 AM ~04/20/10 02:13:33 AM ~07/17/10 01:00:05 PM ~
+09/01/10 11:10:15 PM
INT~05/23/10 11:11:11 PM ~01/08/10 10:45:12 PM ~05/15/09 03:29:37 AM ~
+05/18/09 12:59:59 PM

[download]

In reply to Re: Need help comparing 4 dates by jwkrahn
in thread Need help comparing 4 dates by dirtdog

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