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<?php $arr = [ ['level' => 1, 'data' => [['level' => 2],['level' => 3, 'data' => [['level' => 6]]]]], ['level' => 4], ['level' => 9, 'data' => [['level' => 8]]], ]; function flat($data, &$list = []) { foreach ($data as $key => $value) { if (isset($value['data']) && is_array($value['data'])) { $tmp = $value['data']; unset($value['data']); flat($tmp, $list); } $list[] = $value; } return $list; } print_r(flat($arr));
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 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 ( [0] => Array ( [level] => 2 ) [1] => Array ( [level] => 6 ) [2] => Array ( [level] => 3 ) [3] => Array ( [level] => 1 ) [4] => Array ( [level] => 4 ) [5] => Array ( [level] => 8 ) [6] => Array ( [level] => 9 ) )

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93.5 ms | 2142 KiB | 4 Q