PHP regex title conversion / negative look ahead / toLowerCase

Question

I'm trying to convert some titles in my html pages to <h2>. The pattern is simple.

<?php
$test = "<p><strong>THIS IS A TEST</strong></p><div>And this is Random STUFF</div><p><strong>CP</strong></p>";
$pattern = "/<p><strong>([A-Z ]*?)<\/strong><\/p>/";
$replacement = "<h2>$1</h2>";
$test = preg_replace($pattern, $replacement, $test);
?>

Basically, grab anything that's between <p><strong></strong></p> that is capitalized. Easy enough, so here's the complicated bit.

Firstly, I need to make a single exception. <p><strong>CP</strong></p> must not be converted to <h2>. I tried adding ?!(CP) right after the <p><strong> but it doesn't work.

Secondly, I need to be able to make the first letter capitalized. When I use "ucfirst" with "strtolower" on the preg_replace (ex:ucfirst(strtolower(preg_replace($pattern, $replacement, $test)));), it makes all the characters in the string to lowercase and ucfirst doesn't work as it's detecting "<" to be the first character.

Any hints or am I even going in the right direction?

---

EDIT

Thanks for the help, it was definitely better to use preg_replace_callback. I found that all my titles were more than 3 characters so I added the limiter. Also added special characters. Here's my final code:

$pattern = "/<p><strong>([A-ZÀ-ÿ0-9 ']{3,}?)<\/strong><\/p>/";
$replacement = "<h2>$1</h2>";
$test[$i] = preg_replace_callback($pattern, create_function('$matches', 'return "<h2>".ucfirst(mb_strtolower($matches[1]))."</h2>";'), $test[$i]); 

Answer 1

Try http://php.net/manual/de/function.preg-replace-callback.php .

You can create a custom function that is called on every match. In this function you can decide to a) not replace CP and b) to not put $1, but ucfirst.

Hope this helps & good luck.