subroutine array empty

davidov0009 has asked for the wisdom of the Perl Monks concerning the following question:

I am writing a quick subroutine to grab a list of files in a directory and return it as an array to be used in a select list for CGI::FormBuilder. I cannot seem to get the array to populate itself, even though I have searched through this simple test program I have written and it runs without errors, just does not print anything. Any help appreciated.

#!/usr/bin/perl

use strict;

my $dir = '/home/music';
my @mp3 = getSongs($dir);

foreach my $song (@mp3) {
        print "$song\n";
}

sub getSongs {
        my $dir = @_;
        use Carp;
        my @files;
        if (-d $dir) {
                opendir(MP3, $dir) || croak("Cannot open directory: $d
+ir");
                @files = readdir(MP3);
                closedir(MP3);
        }
return @files;
}
[download]

use strict;
use CGI;
[download]

Comment on subroutine array empty Select or Download Code

Replies are listed 'Best First'.
Re: subroutine array empty by merlyn (Sage) on Dec 08, 2007 at 22:40 UTC
`my $dir = @_;` [download] That's most likely setting $dir to "1" (scalar context applied), and then skipping the rest of the subroutine because you don't have a directory named "1". -- Randal L. Schwartz, Perl hacker	[reply] [d/l]
Re: subroutine array empty by graff (Chancellor) on Dec 09, 2007 at 01:02 UTC
I am writing a quick subroutine to grab a list of files in a directory and return it as an array... Just a side note: since the caller knows which directory is supposed to be scanned (and should also know that it's looking only for files whose names match ".mp3" or something to that effect), there's no need for a subroutine call. The code that would call your subroutine could just do this instead: `my @mp3files = <$path/.mp3>;` [download] (assuming that $path is what would have been passed when calling your subroutine). That use of angle brackets in perl is referred to as a "file glob".	[reply] [d/l]
Re^2: subroutine array empty by davidov0009 (Scribe) on Dec 09, 2007 at 04:47 UTC
Thank you so much for your quick replies. I knew it had to be something so simple I was messing up. I've been using CPAN modules so much writing my own subs has gotten rusty... That file glob is great and just what I needed, so simple. I'm going to strip off the directory name using some regexp's and then I'm good to go. `use strict; use CGI;` [download]	[reply] [d/l]
Re: subroutine array empty by mwah (Hermit) on Dec 08, 2007 at 22:50 UTC
The error in your code has been already pointed out by merlyn and somebody else (how fast are these people ;-), but I'd like to add a more "idiomatic" version of your code. You should return mp3 files only (if you are after them ;-) ... `#!/usr/bin/perl use strict; use warnings; use Carp; my $dir = '/home/musc'; my @mp3 = getSongs( $dir ); for my $song (@mp3) { print "$song\n"; } sub getSongs { my $dir = shift; my @files; if( -d $dir ) { opendir(my $dirhandle, $dir) or croak "$dir $!"; @files = grep /\.mp3$/, readdir $dirhandle; closedir $dirhandle } else { carp "don't know about $dir\n" } return @files; }` [download] Regards mwa	[reply] [d/l]
Re: subroutine array empty by Anonymous Monk on Dec 08, 2007 at 22:41 UTC
instead of `sub getSongs { my $dir = @_; # INCORRECT: assigns @_ in SCALAR context ... } # end of subroutine definition` [download] try `my ($dir) = @_; # assign @_ in list context` [download]	[reply] [d/l] [select]