3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = [ [1, 2, 3], [4, 5, 6] ]; var_export( array_map( fn($row) => array_merge(['X'], $row), $array ) );
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
array ( 0 => array ( 0 => 'X', 1 => 1, 2 => 2, 3 => 3, ), 1 => array ( 0 => 'X', 1 => 4, 2 => 5, 3 => 6, ), )

preferences:
144.54 ms | 403 KiB | 123 Q