Online PHP editor | output for afGvZ

<?php $array1 = [ 31 => ['a', 'b'], 49 => ['c', 'd'], 28 => ['e', 'f'] ]; $array2 = [1, 2, 3]; function mapper($array1, $array2) { $i = -1; var_export( array_map(fn($row) => array_merge($row, [$array2[++$i]]), $array1) ); } function looper($array1, $array2) { $i = -1; foreach ($array1 as &$row) { array_push($row, $array2[++$i]); } var_export($array1); } function walker($array1, $array2) { $i = -1; array_walk($array1, fn(&$row, $k) => array_push($row, $array2[++$i])); var_export($array1); } mapper($array1, $array2); echo "\n---\n"; looper($array1, $array2); echo "\n---\n"; walker($array1, $array2);