- var_dump: documentation ( source)
- preg_replace_callback: documentation ( source)
<?php
$pattern = '/((?<!\w)#\w+)/i';
$subject = <<<EOT
Blablalb #toto zdjsdf #ho_yeah
EOT;
$result = [];
preg_replace_callback('/((?<!\w)#\w+)/i', function ($matches) use(&$result) {
var_dump($matches);
}, $subject);
var_dump($result);