# this searches on Date1
my @sorted_list = sort {
   ${split(/_/,$a)}[0] cmp ${split(/_/,$b)}[0] } @list;
       # [0] is Date1, [1] is Date2, [2] is type.asp
[download]

my @sorted_list = 
   map { $_[0] }
   sort { date_compare($a[1],$b[1]) }  
      # [1] is Date1, [2] is Date2, [3] is the type.asp
   map { [ $_, split /_/ ] } @list;
[download]

Hmmm, I don't think you can assume anything about the date unless you see examples. Date could be in many different formats.

Unless actual example and type of sort requested is posted by wstarrs, I don't think we can be that specific :)

.02

cLive ;-)

Masem wrote:

    ${split(/_/,$b)}[0] }
[download]

To be certain, I tried it, but it doesn't give me the first field of a split. Did you mean:

    [split /_/, $b]->[0]
[download]

?

(This is what I usually do, but maybe there is a better Way out there....)

Jeroen
"We are not alone"(FZ)

Even shorter (and faster) is: (split /_/, $b)[0]

        - tye (but my friends call me "Tye")

Don't know if this is the most efficient:

my @files = qw{ Date12_type.asp Date1_type.asp Date7_type.asp Date4_ty
+pe.asp };

my @sorted_files = map  { join '', @{$_} }
                   sort { $a->[1] <=> $b->[1] }
                   map  { [(/([^\d]+)(\d+)(.*)/)] } @files;
$,="\n";
print @sorted_files;
[download]

The above code prints:

Date1_type.asp
Date4_type.asp
Date7_type.asp
Date12_type.asp
[download]

I was just guessing as to the file names, as the example you provided was unclear to me. The actual regular expression may need to be adjusted. Also, the sort has been done numerically, which is what I guessed you wanted.

If this doesn't get it done, post some filename samples along with sample sorted output.

Cheers,
Ovid

Update: I think Masem gave a clearer (and better) answer. Vote for him.

Update 2: cLive ;-) pointed out that I probably misread your post and, as a result, my sort won't work. Again, post some filenames and the expected sort order, and we can better answer this.

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# sample data
my @filenames = '20001212_20011212_text.asp',
                '20021212_20031212_text.asp',
                '20031212_20041212_image.asp',
                '20011212_20021212_image.asp');

# loop
for (sort { sort_me(); } @filenames) {
  # whatever
  print "$_\n";
}

sub sort_me {

  # grab info from special vars $a and $b
  my ($a_date1,$a_date2) = split '_', $a;
  my ($b_date1,$b_date2) = split '_', $b;

  # then do your sort - eg, to sort by date1 then date2
  # (in the date format I have used above)
  ($a_date1 <=> $b_date1)
  ||
  ($a_date2 <=> $b_date2);
}
[download]

$a and $b are special vars used within a sort. Read this for more info.

Note, this is a rough demo - not gonna test it unless you supply actual data and comparisons... but should give you an idea where to start.

cLive ;-)

Update - just realised you don't need to know type, so have amended code accordingly. later one, removed semi-colon that didn't affect outcome, but still looked out of place...