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run code in 200+ php & hhvm versions
Bugs & Features
<?php $string = 'string_snake_string'; $res = preg_replace_callback('/\_(.)/', function($match) { var_dump($match); return ucfirst($match); }, $field); var_dump($res);
based on DcvU5
Output for 5.6.0 - 5.6.30, hhvm-3.15.4, 7.0.0 - 7.3.0beta1
Notice: Undefined variable: field in /in/kYIlA on line 7 string(0) ""