Re: Grouped characters inside character class.

This works:

use strict;
use warnings;
my $source = 'Posted by mad max beyond eggdome on September 04, 2003';

if ( $source =~ /^Posted by (.*?) on /i ) {
  print qq("$1") . "\n";
}
[download]

which matches:


C:\>perl -MYAPE::Regex::Explain -e "print YAPE::Regex::Explain->new(qr
+/^Posted by (.*?) on /)->explain()"
The regular expression:

(?-imsx:^Posted by (.*?) on )

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  Posted by                'Posted by '
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    .*?                      any character except \n (0 or more times
                             (matching the least amount possible))
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
   on                      ' on '
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
[download]

-enlil

Comment on Re: Grouped characters inside character class. Select or Download Code

Replies are listed 'Best First'.
Re^2: Grouped characters inside character class. by m.att (Pilgrim) on Jun 02, 2006 at 01:49 UTC
The only issue with this regex (and the poster's original idea as well) is it will not properly capture the username if it contains ' on '. For example: `my $source = 'Posted by getting on your nerves on September 04, 2003';` It's probably a good idea to anchor on more than just the ' on ' part like: `my $source = 'Posted by getting on your nerves on September 04, 2003'; if ($source =~ /Posted by (.+?) on \w+ \d{2}, \d{4}$/) { ... }` [download] Regards m.att	[reply] [d/l] [select]
Re^3: Grouped characters inside character class. by Enlil (Parson) on Jun 02, 2006 at 02:13 UTC
The only issue with this regex (and the poster's original idea as well) is it will not properly capture the username if it contains ' on ' Noted. So we capture up until the last ' on '. `use strict; use warnings; my $source = 'Posted by getting on my nerves on September 04, 2003'; if ( $source =~ /^Posted by (.?) on (?!. on )/i ) { print qq("$1") . "\n"; }` [download] blokhead is right.. and I will go lick my wounds now.	[reply] [d/l]
Re^4: Grouped characters inside character class. by blokhead (Monsignor) on Jun 02, 2006 at 02:56 UTC
That's the same as just being greedy: `/^Posted by (.*) on /i` [download] blokhead	[reply] [d/l]
Re^2: Grouped characters inside character class. by the_0ne (Pilgrim) on Jun 02, 2006 at 01:45 UTC
Thanks enlil for the response. That does work. My only problem is, I've been warned on perlmonks several times of using .*. I guess in this case it would be fine though because I do want everything grabbed up until the (space)on(space). Maybe I was just trying to be too fancy. :)	[reply]


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