3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php $embedCode = '<iframe width=800> </iframe>'; echo preg_replace('~(<iframe[^>]*\swidth=["\']?)(\d+)(["\']?\s?.*)~', '${1}' . '666' . '${3}', $embedCode);
based on WFcPT
Output for 4.3.0 - 7.2.0
<iframe width=666> </iframe>