$re = '/\bc\">(.+)<\/a/';
$str = '<h3 class="r"><a class="pstl" data-what="1" href="http://www.google.de/aclk?sa=l&ai=C-9oQygENVpujKqGXzAOfn... jsaction="spop.c">10 x Leitz Stehsammler 24230095 DIN A476mm Hartpappe RC schwarz</a></h3>';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php