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<?php $a = [1,2,3,4]; $b = [ 1=>[ 2=>[ 3=>[ 4=>[] ] ] ] ]; $tmp = []; foreach ($a as $val) { if ($tmp) { if (isset($tmp[$val])) { $tmp = &$tmp[$val]; } else { break; } } else { $tmp = &$b[$val]; } } $tmp = ['aaaa']; var_dump($tmp); var_dump($b);
Output for 7.3.0 - 7.3.33, 7.4.0 - 7.4.30, 8.0.0 - 8.0.20, 8.1.0 - 8.1.7
array(1) { [0]=> string(4) "aaaa" } array(1) { [1]=> array(1) { [2]=> array(1) { [3]=> array(1) { [4]=> &array(1) { [0]=> string(4) "aaaa" } } } } }

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