3v4l.org

run code in 300+ PHP versions simultaneously
<?php $mainArray = array(23 => array(21,23,20), 21 => array(21,23,23), 24 => array(21,23,20)); $newArray = array(); foreach($mainArray as $key => $value) { if (in_array(20, $value)) { $newArray[] = $key; } } echo var_dump($newArray);
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.29 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
array(2) { [0]=> int(23) [1]=> int(24) }
preferences:
203.11 ms | 406 KiB | 352 Q