3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $embedCode = '<iframe width="800" > </iframe>'; echo preg_replace('/(<iframe[^>]*\swidth=")(\d+)("\s.*)/', '${1}' . '666' . '{3}', $embedCode);
based on mggKA
Output for 4.3.0 - 5.6.28, hhvm-3.10.0 - 3.13.2, 7.0.0 - 7.1.0
<iframe width="666{3}