Regular Expression Help - Weird Results

[AMT2K5]

Hello, I have a function that will so far convert an mp3 filename from
Track-Artist_moreartist.mp3

to Artist_moreartist_Track.mp3

*Where more artist is like Pink_Floyd not Queen*

I am getting weird results with my regular expression result

my @dir_contents = @_[0];
foreach(@dir_contents)
{
my $old = $_;
my $track;
my $artist;
my $fullTitle;

$old =~ m/-/;
$track = $`;

my $position = rindex($_ ,"-") + 1;

$artist = substr($_,$position);
$artist =~ s/\.mp3//;
$artist =~ s/^\s+//;
$artist =~ s/\s+$//;

$track =~ s/^\s+//;
$track =~ s/\s+$//;

$fullTitle = $artist."-".$track.".mp3";

return $fullTitle;

}

Original is Echoes-Derek_Duke.mp3

My result is (whitespace at the begining still)
\sDerek_Duke-Echoes.mp3 -.mp3

Appreciate any help whatsoever.

-Aaron

 

[AMT2K5]

The return is there for now to test one file name.

I am displaying it elsewhere

 

[Matt Garrish]

The return is there for now to test one file name.

The return is where?

I am displaying it elsewhere

Well, I'm glad you're not showing it off in public.

Please put enough context in your posts for people to understand what you're
talking about.

Matt

 

[it_says_BALLS_on_your_forehead]

Hello, I have a function that will so far convert an mp3 filename from
Track-Artist_moreartist.mp3

to Artist_moreartist_Track.mp3

*Where more artist is like Pink_Floyd not Queen*

try (untested).

my $song =~ s/(\w+)-(\w+)_(\w+)/$2_$3_$1/;

 

[it_says_BALLS_on_your_forehead]

try (untested).

my $song =~ s/(\w+)-(\w+)_(\w+)/$2_$3_$1/;

make that:


my $song = 'Echoes-Derrick_Pink_Floyd.mp3';
print "$song\n";
$song =~ s/(\w+)-(\w+)_(\w+)/$2_$3_$1/;
print "$song\n";

 

[it_says_BALLS_on_your_forehead]

make that:


my $song = 'Echoes-Derrick_Pink_Floyd.mp3';
print "$song\n";
$song =~ s/(\w+)-(\w+)_(\w+)/$2_$3_$1/;
print "$song\n";

hehe, actually, make that:
$song =~ s/(\w+)-(\w+)/$2_$1/;

 

[Eric J. Roode]

foreach(@dir_contents)
{
my $old = $_;

There is a shorter, simpler notation for the above:

foreach my $old (@dir_contents)

$old =~ m/-/;
$track = $`;

my $position = rindex($_ ,"-") + 1;

$artist = substr($_,$position);
$artist =~ s/\.mp3//;
$artist =~ s/^\s+//;
$artist =~ s/\s+$//;

$track =~ s/^\s+//;
$track =~ s/\s+$//;

You're not using regular expressions to help you as much as you could.
All you're using the regexes for is to find a hyphen (why do you use m/-/
one time, and rindex the other?), and to trim bits off of the pieces you
do find.

Try "capturing" in your regex. That means using parentheses around bits
of your regex; this causes the parenthesized bits to be returned (in list
context). See:

($track, $artist) = $old =~ /(.*?)-(.*)/;

(ASIDE: you should always (yeah, always) check to see if the regex
succeeded:

unless (($track, $artist) = $old =~ ....)
{ ... handle non-match ... }
END ASIDE)

With capturing, you can be more specific about your matching:

($track,$artist) = $old =~ /\A\s*(.*?)\s*-\s*(.*?)\s*(\.mp3)?\s*\z/;

Now, that's a pretty incomprehensible bit of line noise, isn't it? But
that's why they invented the 'x' modifier. It lets you insert arbitrary
whitespace and comments into regular expressions. Use it. Use it often.

($track,$artist) = $old =~
/
\A # beginning of string
\s* # Optional leading whitespace
(.*?) # track name
\s* - \s* # separator (with optional whitespace)
(.*?) # artist name
\* # optional trailing whitespace
(\.mp3)? # optional ".mp3" suffix
\s* # optional trailing whitespace
\z # end of string
/x; # end of regex. Note x modifier.


--
Eric
`$=`;$_=\%!;($_)=/(.)/;$==++$|;($.,$/,$,,$\,$",$;,$^,$#,$~,$*,$:,@%)=(
$!=~/(.)(.).(.)(.)(.)(.)..(.)(.)(.)..(.)......(.)/,$"),$=++;$.++;$.++;
$_++;$_++;($_,$\,$,)=($~.$"."$;$/$%[$?]$_$\$,$:$%[$?]",$"&$~,$#,);$,++
;$,++;$^|=$";`$_$\$,$/$:$;$~$*$%[$?]$.$~$*${#}$%[$?]$;$\$"$^$~$*.>&$=`