- var_dump: documentation ( source)
- preg_match: documentation ( source)
<?php
$s = "http://ad.zanox.com/ppc/?22535376C937109894&ULP=[[?etf-name=Zanox%20-%20Flux&etf-prdref=0000011028nubuck%20kaki&eurl=http%3A%2F%2Fwww.sarenza.pl%2Fbirkenstock-madrid-flor-w-s780328-p0000011028]]";
//$t = stristr($s,"&eurl",true);
//str_replace("[[","",stristr($t,"[["));
preg_match("/(prdref=)(.*?)(&eurl)/",$s,$match);
var_dump($match[4]);
?>