simple perl question.

Creamy Goodness · 04-12-2008 09:02PM #1

i have an array populated with files of the current directory now the directory contains the following files (numbers are random).

00
200
77
100
12
23
99
90
myperlfile.pl
mytext.txt

i want to get the array populated only by the files denoted by the digits.

this is what i have so far.

[php]
my @filelist = <*>;

my @temp;

foreach my $file (@filelist)
{
if($file =~ m/^[0-9]*$/)
{
push(@temp, $file);
}
}

@filelist = @temp;
@filelist = sort(@filelist);

foreach my $filelist (@filelist)
{
print $filelist;
}
[/php]

this seems to work but the sort doesn't work like i want it too.

on the above directory listing the above will print

00 100 12 200 22 23 77 90 99

where as i'd like it printed like this:

00 12 22 23 77 90 99 100 200

what i ultimately want to end up with is two variables with the lowest and highest value i.e. in the above example 00 200

is there a simpler way of doing this? as i think i've went a bit nuts with it?

Tom Dunne · 04-12-2008 09:16PM

Ah yes, the perennial ASCII value vs. numeric value problem.

What it's doing is correct - it's ignoring the numeric value and sorting them on ASCII values. Convert the number portions to numbers and it will sort correctly. Can't remember how to do it, it's been a while since I looked at perl.

I actually did this in SQL only there a few weeks back.

Webmonkey · 05-12-2008 02:24AM

Tom Dunne wrote: »

Ah yes, the perennial ASCII value vs. numeric value problem.

What it's doing is correct - it's ignoring the numeric value and sorting them on ASCII values. Convert the number portions to numbers and it will sort correctly. Can't remember how to do it, it's been a while since I looked at perl.

I actually did this in SQL only there a few weeks back.

To follow on from this:

[php]

my @filelist = <*>;

my @temp;

foreach my $file (@filelist)
{
if($file =~ m/^[0-9]*$/)
{
push(@temp, $file);
}
}

@filelist = @temp;
@filelist = sort (sortByNumber @filelist); # Use custom comparer function

foreach my $filelist (@filelist)
{
print $filelist;
}

sub sortByNumber
{
$a <=> $b; # <--- numeric compare
}

[/php]

Havn't tried it but I presume it works, though it quite late...

Creamy Goodness · 05-12-2008 11:58AM

superb guys, after a bit of googling after Tom's post i came across your solution Webmonkey.

Cheers.

knackee · 05-12-2008 02:43PM

print join "\n", sort { $a <=> $b } grep { /^\d+$/ } <*>;

From right to left:
1) <*> get all files
2) grep (find) all numeric filenames
3) sort numerically
4) print results separated by newlines

Creamy Goodness · 16-12-2008 10:57AM

ok, hit another snag on this.

i've got it down to the numeric files will only be in the range of 1..20 or 1..X.

now what i have at the moment is i can run my perl file like so.

[php]perl myperlfile.pl -d 13[/php]

and that will delete file 13 from the directory. what i would like is that when this action is done i want file 14,15,16,17,18,19,20 to be renamed to 13,14,15,16,17,18,19.

i'm not at the machine now that contains the script but looking for pointers on how to go about doing this.

what i was thinking was reading the directory contents like before into an array, deleting the file, then reading the contents of the directory again and doing some compare between the two?

simple perl question.

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