Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.php > #6992 > unrolled thread

Dynamic backreferences, finding last in a group

Back to article view | Back to comp.lang.php

Contents

  Dynamic backreferences, finding last in a group Jason C <jwcarlton@gmail.com> - 2012-09-09 03:31 -0700
    Re: Dynamic backreferences, finding last in a group Anders Wegge Keller <wegge@wegge.dk> - 2012-09-09 13:51 +0200
      Re: Dynamic backreferences, finding last in a group Scott Johnson <noonehome@chalupasworld.com> - 2012-09-09 07:16 -0700

#6992 — Dynamic backreferences, finding last in a group

I'm working with preg_replace(), like so:

$pattern = array();
foreach ($filter as $org)
  array_push($pattern, "/((<br>|\s)*)$org(er|in|...)/i");

$text = preg_replace($pattern, '$1$new$3', $text);


The issue I'm having is when $org contains a regex expression, like:

(D|d)ear

in which case (er|in|...) would now be $4 instead of $3.

The question is, is there a way that I can dynamically find the last backreference in the pattern, instead of referring to it strictly by number?

If not, I could always check to see if $org contains a (...), and then set the number accordingly. But this is in a foreach loop, and putting an strpos() in a loop like that seems slow; and then, I'm not sure that a backreference like this would works. Like:

if (strpos...) $num = "4";
else $num = "3";

$text = preg_replace($pattern, '$1$new$$num', $text);

Any suggestions?

[toc] | [next] | [standalone]

#6993

Jason C <jwcarlton@gmail.com> writes:

> Any suggestions?

Read the manual on regexp syntax, and use named patterns.

-- 
/Wegge

Leder efter redundant peering af dk.*,linux.debian.*

[toc] | [prev] | [next] | [standalone]

#6994

On 9/9/2012 4:51 AM, Anders Wegge Keller wrote:
> Jason C <jwcarlton@gmail.com> writes:
>
>> Any suggestions?
>
> Read the manual on regexp syntax, and use named patterns.
>

Wow that is a very good feature I never know about.

This I can imagine will come in very handy.

Thanks
Scotty


Example #4 Using named subpattern
<?php

$str = 'foobar: 2008';

preg_match('/(?P<name>\w+): (?P<digit>\d+)/', $str, $matches);

/* This also works in PHP 5.2.2 (PCRE 7.0) and later, however
  * the above form is recommended for backwards compatibility */
// preg_match('/(?<name>\w+): (?<digit>\d+)/', $str, $matches);

print_r($matches);

?>

The above example will output:

Array
(
     [0] => foobar: 2008
     [name] => foobar
     [1] => foobar
     [digit] => 2008
     [2] => 2008
)

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.php

csiph-web