3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = [ 'row1' => 'row1', 'row2' => '', 'row3' => '', 'row4' => 'row4', ]; var_export( array_combine( array_keys($array), array_filter($array) + $array ) );
Output for 8.1.32 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
array ( 'row1' => 'row1', 'row2' => 'row4', 'row3' => '', 'row4' => '', )
preferences:
60.18 ms | 844 KiB | 4 Q