- array_map: documentation ( source)
- json_encode: documentation ( source)
<?php
$first = array(1,2,3);
$last = array(4,5,6);
$k = 10;
$array = array_map(function ($first, $last) { return array("first" => $first, "last" => $last); }, $first, $last);
echo json_encode(array('id' =>$k, 'name' => $array));