3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $pattern = '\d+'; $haystack = '0123 456 789'; preg_replace_callback($pattern, 'add_three', $haystack); function add_three($matches){ return '777'; }
Output for 4.3.11 - 5.6.28, 7.0.0 - 7.1.0
Warning: preg_replace_callback(): Delimiter must not be alphanumeric or backslash in /in/OlOSv on line 6
Output for 4.3.0 - 4.3.10, hhvm-3.10.0 - 3.12.0
Warning: Delimiter must not be alphanumeric or backslash in /in/OlOSv on line 6