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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 ( ) */

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