Online PHP editor | output for alenU

<?php define('VALIDTYPES', [ 'double' => 'd', 'integer' => 'i', 'resource' => 'b', // I haven't actually researched/tested this 'string' => 's', ]); $params = [1, -3.5, 'stringy', (object)[]]; $params = [1, -3.5, 'stringy']; $types = array_reduce( $params, function($carry, $item) { $type = gettype($item); if (!isset(VALIDTYPES[$type])) { throw new Exception('unexpected data type'); } else { return $carry . VALIDTYPES[$type]; } }, ''); var_export($types);