3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = array('a' => 'Hello', 'b' => 'World'); array_walk($array, 'adda'); function adda(&$value, &$key) { $key = "a".$key; }
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Warning: adda(): Argument #2 ($key) must be passed by reference, value given in /in/uIJpg on line 4 Warning: adda(): Argument #2 ($key) must be passed by reference, value given in /in/uIJpg on line 4
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.17 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33

preferences:
252.08 ms | 405 KiB | 382 Q