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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 ruWqC
Output for 4.3.0 - 7.1.0
<iframe width="666"> </iframe>