allendevans:

I've not found a "search and replace" command to replace the commas with "nothing", allowing direct numeric manipulation of the scalar variables.

Really?

$ cat t.pl
#/usr/bin/perl
use strict;
use warnings;
use feature ':5.10';

my $t = "1,234,567.89";
$t =~ s/,//g;
say $t;

$ perl t.pl
1234567.89
[download]

...roboticus

When your only tool is a hammer, all problems look like your thumb.

You can use tr or the substitution operator (see perlretut) to remove the commas.

But it's way easier to get the list of files from glob or opendir, readdir, closedir, and the file size from -s or stat.

But it's way easier to get the list of files ...

And fail the course for not doing the homework

# remove commas from $filesize string
# ===================================
$filesize =~ s/,//;
[download]

ramlight,

Thanks for your post! I'm having the best success with your suggestion, some others caused perl to crash. :(

I pasted the snippet into my script ...

# while not eof
# =============
while ($line = <INPUT>) {

($date, $time, $ampm, $filesize, $filename) = split(" ", $line);

# remove commas from $filesize string
# ===================================
$filesize =~ s/,//;
[download]

and it successfully removed the first comma. (below)

Results from gnome-terminal:

1572,727,014    IN11-135.E01
1223    IN11-135.E01.txt
1572,694,696    IN11-135.E02
1572,740,428    IN11-135.E03
1572,785,002    IN11-135.E04
1572,696,748    IN11-135.E05
1572,745,871    IN11-135.E06
1572,737,726    IN11-135.E07
1572,785,459    IN11-135.E08
1572,777,135    IN11-135.E09
1572,751,922    IN11-135.E10
1572,684,462    IN11-135.E11
1556,456,660    IN11-135.E12

Total Files: 13  Avg Size: 0
[download]

The first comma was removed from each number. Now I'm off to perldoc.perl.org to see how I can remove the remaining commas.

Thanks ... Allen.

Have another read of the answer roboticus gave you, paying particular attention to the 'g' flag of the substitution.

Cheers,

JohnGG

The first comma was removed from each number.

The s/// operator by default removes only the first match. So:

my $var = "foobarfoobaz";
$var =~ s/foo//;
say $var;   # says "barfoobaz"
[download]

There are various flags you can include to alter its default behaviour though. One of the most useful is the "g" (global) flag...

my $var = "foobarfoobaz";
$var =~ s/foo//g;
say $var;   # says "barbaz"
[download]

Note that the slashes may be replaced with other characters, so you could equally write:

my $var = "foobarfoobaz";
$var =~ s@foo@@g;
say $var;   # says "barbaz"
[download]

Or even:

my $var = "foobarfoobaz";
$var =~ s{foo}{}g;
say $var;   # says "barbaz"
[download]

... which some people might find more readable. Though note that there are a handful of characters (hash, question mark and single quote spring to mind) that trigger special behaviours here (perlop has more details).

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

Dear allendevans,

# unnecessary in perl, but good coding habits are tough to make

Well that jumps out at me, since there are some very good coding habits for Perl also!

roboticus showed you the way you should write your code by scoping your variables with 'my' or 'local' or 'our'. If you had 'use strict' as roboticus had, your script would not compile and you would have the opportunity to write better Perl code. It is not that you pre-defined your variables, but that somehow that makes for better coding habits.

Do you think this code?

$date = "";
$time = "";
$ampm = "";
$filesize = 0;
$filename = "";
[download]

my ($date, $time, $ampm, $filesize, $filename) = split(" ", $line);
[download]

Good Luck!

flexvault,

Thanks for taking the time to read my post and script. The comment is a quip for the professor, who made an off-hand comment during the lecture about declaring variables.

Which is the better way of declaring variables ... that depends on what the compiler (or professor, or employer) wants! I do feel more at ease declaring my variables beforehand, though. legacy feelings of inadequacy left over from previous programming languages ... :)

Thanks ... Allen.

Were I your professor, I'd mark that quip down, since it's attached to a method of declaring variables that's legal, but falls far short of 'best practice.'

Perl is not one of your "previous programming languages" and your response to your own rhetorical question about "the better way of declaring variables" isn't quite 'on-target' here. Perl (well, thru 5.10, IIRC) will accept the way you've done it, without even suggesting that there's a better way... which involves understanding scope... and the best practice of limiting a variable's scope as narrowly as possible.

Best practice for declaring variables varies from programming language to programming language. But the declaration you used is very far from best practice in Perl.

When declaring a variable you in Perl, it is best practice to declare whether it's a lexical (my) or package (our) variable. e.g.:

my $counter = 0;

It's also best practice to declare the variable in the tightest possible scope. For example, if a variable is used inside a loop, and needs reinitialising each time round the loop, then declare it inside the loop, not before the loop.

Find the bug here:

use 5.010;
use strict;

my $gender = 'unknown';
while (<DATA>)
{
  chomp;

  given ($_) {
    when ("Alice")  { $gender = 'female' }
    when ("Annie")  { $gender = 'female' }
    when ("Andy")   { $gender = 'male' }
    when ("Arnold") { $gender = 'male' }
  }

  say "$_ is $gender.";
}
__DATA__
Alice
Andy
Arnold
Jennifer
Annie
Henry
[download]

Output is:

Alice is female.
Andy is male.
Arnold is male.
Jennifer is male.
Annie is female.
Henry is female.

Why is Jennifer male? Why is Henry female? It's because $gender is declared outside the loop, so is allowed to stay alive between loop iterations. Merely moving the one line where it's declared solves our subtle bug:

use 5.010;
use strict;

while (<DATA>)
{
  chomp;

  my $gender = 'unknown';
  given ($_) {
    when ("Alice")  { $gender = 'female' }
    when ("Annie")  { $gender = 'female' }
    when ("Andy")   { $gender = 'male' }
    when ("Arnold") { $gender = 'male' }
  }

  say "$_ is $gender.";
}
__DATA__
Alice
Andy
Arnold
Jennifer
Annie
Henry
[download]

Alice is female.
Andy is male.
Arnold is male.
Jennifer is unknown.
Annie is female.
Henry is unknown.

Perl variables have some pretty cool features, but they can trip you up. The precaution of adding use strict near the top of each script is generally a wise one. This one line tells Perl to force you to declare all your variables. This doesn't stop you shooting yourself in the foot, but it makes it difficult to shoot yourself in the foot accidentally. (You're still able to shoot yourself in the foot if you put in a bit of effort.)

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

allendevans,

Glad it was from the professor!

Have a good one!

"Well done is better than well said." - Benjamin Franklin

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]

#!/usr/bin/perl --
use strict; use warnings;
use Data::Dump qw/ dd /;
my $line = q{11/21/2010  05:02 AM     1,572,696,748 IN11-135.E05};

#11/21/2010  05:02 AM     1,572,696,748 IN11-135.E05
#1234567890  12345678 12345678901234567 
# date A10   time +A8    size A18       filename the rest
# x2 to ignore spaces between date and time
my( $date, $time, $sizewithcommas, $name ) = unpack "A10 x2 A8 x1 A18 
+ A*", $line;

dd( [ $date, $time, $sizewithcommas, $name ] );


my $raw = q{
03/19/2011  04:01 PM             1,451 filename
09/07/2011  05:15 AM    <DIR>          dirname
};

open my($fh), '<', \$raw ;
while(<$fh>){
   my( $datetime, $filesizeordirindicator, $filename ) = eval { unpack
+ 'A20 A18 x1 A*', $_ };
   warn $@ if $@;
   dd([ $datetime, $filesizeordirindicator, $filename ]);
}
__END__
["11/21/2010", "05:02 AM", "    1,572,696,748", "IN11-135.E05"]
'x' outside of string in unpack at crap line 22, <$fh> line 1.
[undef, undef, undef]
["03/19/2011  04:01 PM", "             1,451", "filename"]
["09/07/2011  05:15 AM", "    <DIR>", "dirname"]
[download]