3v4l.org

run code in 300+ PHP versions simultaneously
<?php $var = array( 'a' => 'a', 'b' => 'b', ); array_walk($var, function ($value) { var_dump($value); }); var_dump(key($var));
Output for 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
string(1) "a" string(1) "b" string(1) "a"
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20
string(1) "a" string(1) "b" NULL
preferences:
165.67 ms | 402 KiB | 183 Q