3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $pattern = '#\d+#'; $haystack = '0123 456 789'; echo preg_replace_callback($pattern, 'add_three', $haystack); function add_three($matches){ return '777'; }
based on lruus
Output for 4.3.0 - 7.1.0
777 777 777