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<?php function direct_product(array ...$arrays) { $result = [[]]; foreach ($result as $i => $x) { foreach ($arrays as $j => $y) { $result[$i][$j] = array_merge($x, [$y]); } } return $result; } var_export(direct_product(['A', 'B', 'C'], ['a'], [1, 2])); /* array ( 0 => array ( 0 => 'A', 1 => 'a', 2 => 1, ), 1 => array ( 0 => 'A', 1 => 'a', 2 => 2, ), 2 => array ( 0 => 'B', 1 => 'a', 2 => 1, ), 3 => array ( 0 => 'B', 1 => 'a', 2 => 2, ), 4 => array ( 0 => 'C', 1 => 'a', 2 => 1, ), 5 => array ( 0 => 'C', 1 => 'a', 2 => 2, ), ) */ var_export(direct_product(['A', 'B', 'C'], [], [1, 2])); /* array ( ) */
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 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 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
array ( 0 => array ( 0 => array ( 0 => array ( 0 => 'A', 1 => 'B', 2 => 'C', ), ), 1 => array ( 0 => array ( 0 => 'a', ), ), 2 => array ( 0 => array ( 0 => 1, 1 => 2, ), ), ), )array ( 0 => array ( 0 => array ( 0 => array ( 0 => 'A', 1 => 'B', 2 => 'C', ), ), 1 => array ( 0 => array ( ), ), 2 => array ( 0 => array ( 0 => 1, 1 => 2, ), ), ), )

preferences:
156.78 ms | 405 KiB | 182 Q