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run code in 200+ 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 '-'.$matches[0].'-'; }
based on IPGuP
Output for 4.3.0 - 7.2.0
-0123- -456- -789-