3v4l.org

run code in 300+ PHP versions simultaneously
<?php $def = array( 1 => 1, 2 => 1, 3 => 1); $fill = array( 2 => 0 ); $res = array_merge($fill, $def); print_r($res);
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 - 7.1.20, 7.2.0 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
Array ( [0] => 0 [1] => 1 [2] => 1 [3] => 1 )

preferences:
231.81 ms | 405 KiB | 355 Q