3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php $str = 'e ,a\\,b\\\\,c\\\\\\,d\\\\'; preg_match_all("/(?<=(INVO[a-z]+\sNO\s))(\d+)\b/i","INVOCE NO 234", $matches); var_dump($matches[0]);
based on VdkB0
Output for 5.4.0 - 7.2.0
Warning: preg_match_all(): Compilation failed: lookbehind assertion is not fixed length at offset 22 in /in/SO68q on line 3 NULL