Don't comment what the code tells you it does no matter how wonderfull the code seems to be. You can almost guarantee that if you choose good variable names and write clean code your tutor will have no trouble understanding it without comments. It's even possible the tutor may actually be able to see the code instead of being overwelmed by comments.

Always use strictures (use strict; use warnings;). That on its own would pick up at least one set of bugs in your code. Declare your variables in the smallest scope that you can (other replies have already said that so it must be true) - that with strictures would pick up another bug for you.

Use the three parameter version of open and lexical file handles (declared with my).

Use indentation to reflect the structure of your code - indent one level for each nested block.

The following code illustrates these points. Note that there are several bugs left in this code that will show up due to strictures when you run it. Do not put your name on this code and hand it in unless you want low marks!

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

my $file = <<'FILE';
 Directory of E:\DOM\D2\HDD\IN11-135

04/04/2011  11:29 PM    <DIR>          .
04/04/2011  11:29 PM    <DIR>          ..
11/21/2010  05:02 AM     1,572,727,014 IN11-135.E01
11/21/2010  05:02 AM             1,223 IN11-135.E01.txt
11/21/2010  05:02 AM     1,572,694,696 IN11-135.E02
11/21/2010  05:02 AM     1,572,740,428 IN11-135.E03
11/21/2010  05:02 AM     1,572,785,002 IN11-135.E04
11/21/2010  05:02 AM     1,572,696,748 IN11-135.E05
11/21/2010  05:02 AM     1,572,745,871 IN11-135.E06
11/21/2010  05:02 AM     1,572,737,726 IN11-135.E07
11/21/2010  05:02 AM     1,572,785,459 IN11-135.E08
11/21/2010  05:02 AM     1,572,777,135 IN11-135.E09
11/21/2010  05:02 AM     1,572,751,922 IN11-135.E10
11/21/2010  05:02 AM     1,572,684,462 IN11-135.E11
11/21/2010  05:02 AM     1,556,456,660 IN11-135.E12
              13 File(s) 18,856,584,346 bytes
FILE

open my $in, '<', \$file or die "Can't open Lab3.txt\n";

my $numFiles;
my $totalFileSize = 0;

while (my $line = <$in>) {
    my ($date, $time, $ampm, $filesize, $filename) = split(" ", $line)
+;

    $filesize =~ y/,//d;
    $totalFileSize += $filesize;
    ++$numFiles;
}

#printf "%6d %s\n", $filesize, $filename;

if ($numFiles) {
    printf "Total Files: %d, avg Size: %d\n\n", $numFiles, $totalFileS
+ize / $numFiles;
}
[download]