3v4l.org

run code in 300+ PHP versions simultaneously
<?php $tmp = array( 'q1' => 'qwqwqw', 'w2' => 'www', 'r3'=> 'eee', 'u8'=>'333e', ); $tmp = array_merge(array_slice($tmp,0,2), array('third' => 'ddddddddd'),array_slice($tmp,2)); var_dump($tmp);
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.5 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
array(5) { ["q1"]=> string(6) "qwqwqw" ["w2"]=> string(3) "www" ["third"]=> string(9) "ddddddddd" ["r3"]=> string(3) "eee" ["u8"]=> string(4) "333e" }

preferences:
114.34 ms | 403 KiB | 166 Q