3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr1 = array( "0" => 5, "1" => 2, "4" => 67 ); $arr2 = array( "0" => 5, "1" => 2, "8" => 78 ); array_merge($arr2, array_fill_keys(array_diff($arr1, $arr2), 0)); print_r($arr2);

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39.94 ms | 402 KiB | 5 Q