<?php $keys = ['k1', 'k2', 'k3', 'k4']; $res1 = []; // Foreach foreach ($keys as $key) { $res1[$key] = [ 'start' => 1, 'end' => 2, ]; } // array_fill_keys $res2 = array_fill_keys($keys, [ 'start' => 1, 'end' => 2, ]); //array_reduce $res3 = array_reduce($keys, function($acc, $key) { $acc[$key] = [ 'start' => 1, 'end' => 2, ]; return $acc; }, []); print_r($res1); print_r($res2); print_r($res3);