Re: Determing if this regex matched

[toolic]

Use an "if" statement to check the return of s/// (returns the number of substitutions made; false otherwise):

use strict;
use warnings;
my @items = ('"Title Text Example1"', 'Title Text Example2', ' Title T
+ext Example3 ',' "Title Text Example4"');
foreach my $title (@items) {
    my $match = 0;
    $match++ if $title =~ s/^[\s"]+//;
    $match++ if $title =~ s/[\s"]+$//;
    print "$title.\n" if $match;
}

__END__

Title Text Example1.
Title Text Example3.
Title Text Example4.

Updated to match both begin and end.

[cormanaz]

Hey! I had no idea s/// returned anything. Also a more straightforward way to write the regex. Problem is, with the or, the second sub doesn't get executed if the first one matches, so there is still the trailing quote on examples 1 and 4. I suppose one could do

my @items = ('"Title Text Example"', 'Title Text Example', ' Title Tex
+t Example ',' "Title Text Example"');
foreach my $title (@items) {
    my $changed = 0;
    if ($title =~ s/^[\s"]+//) { $changed=1; }
    if ($title =~ s/[\s"]+$//) { $changed=1; }
    if ($changed) {
        print "$title\n";
    }
}

But that doesn't seem very elegant.

[ww]

For the elegant method, try perlretut (and family), "Mastering Regular Expressions," Tutorials, perhaps.

But -- IMO -- "elegant" is frequently overrated; the real question, I think, is "does it work, consistently?"

[cormanaz]

Well good point.

I still wonder why is $& always null in the original example.

[merlyn]

Too much work!

my @items = ('"Title Text Example"', 'Title Text Example', ' Title Tex
+t Example ',' "Title Text Example"');
foreach (@items) {
    if (s/^[\s"]+// or s/[\s"]+$//) {
        print "$_\n";
    }
}

[cormanaz]

That's what toolic had before editing the his post. Doesn't work because if the first element of the or evaluates true the second one doesn't get evaluated, so if there's a quote/space at the beginning, quotes/spaces get left at the end.