3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array=[[8,9,7],[7,8,9,33,21],[11,12,33,21,9,31]]; foreach($array as $sub){ foreach($sub as $v){ if(!isset($result[$v])){ $result[$v]=$v; } } } var_export(array_values($result));
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 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 => 8, 1 => 9, 2 => 7, 3 => 33, 4 => 21, 5 => 11, 6 => 12, 7 => 31, )
preferences:
99.16 ms | 1967 KiB | 4 Q