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<?php $mainArr = [ [125 => 'B', 127 => 'A', 178 => 'Z', 78 => 'G'], [111 => 'X', 127 => 'K', 108 => 'J', 708 => 'P'], [125 => 'L', 127 => 'M', 178 => 'Q', 78 => 'A'], ]; array_walk($mainArr, function(&$subarray) { asort($subarray); }); var_export($mainArr);
Output for 7.2.0 - 7.2.26, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
array ( 0 => array ( 127 => 'A', 125 => 'B', 78 => 'G', 178 => 'Z', ), 1 => array ( 108 => 'J', 127 => 'K', 708 => 'P', 111 => 'X', ), 2 => array ( 78 => 'A', 125 => 'L', 127 => 'M', 178 => 'Q', ), )

preferences:
97.48 ms | 408 KiB | 5 Q