Zielfelder, Robert wrote:
I have a sorting problem I need to solve but I'm not sure how to go
about it. I have an application that dumps a file with a format like
this:
19JAN2006.1503
03JAN2006.1647
19DEC2004.0530
24MAR2003.1115
As you may have guessed, these are dates and times - timestamps for log
files from an application. I want to be able to sort this list from
earliest to latest date. I'm able to parse these into specific
categories (Year, Month, Day, Time) and can sort on any one category,
but I don't know how to sort by multiple categories. Anyone have any
ideas?
I suggest you provide a function that will transform the filenames into
something that's sortable using the standard sort operator. The program below
uses a subroutine 'reformat' which splits the filename into day, month, year,
and time strings, uses a hash to translate the month name into a number, and
glues them all together again in a different order. Once this is written, the
sort block can compare the result of applying the function to its two parameters
and produce a list sorted in date order as required.
Forget about anything fancier than necessary until you find your program is
running too slowly. Hashes and Schwartzian transforms are devices for improving
speed at the expense of clarity.
HTH,
Rob
use strict;
use warnings;
my @file = qw/
19JAN2006.1503
03JAN2006.1647
19DEC2004.0530
24MAR2003.1115
/;
my %month;
@month{qw/JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC/} = '01' .. '12';
foreach ( sort { reformat($a) cmp reformat($b) } @file) {
print $_, "\n";
}
sub reformat {
my $date = shift;
my ($d, $m, $y, $hhmm) = $date =~ /(\d+)([A-Z]+)(\d+)\.(\d+)/;
"$y$month{$m}$d$hhmm";
}
**OUTPUT**
24MAR2003.1115
19DEC2004.0530
03JAN2006.1647
19JAN2006.1503
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