php中ajax实例，用到json

<?php
/**
* Created by PhpStorm.
* User: usa007lhy
* Date: 15-9-9
* Time: 下午7:28
*/
$json_arg = array(
'name'=> $_POST['name'],
'sex'=> $_POST['sex'],
'age'=> $_POST['age'],
);
//$json = new JSON;
$json_result = json_encode($json_arg);
echo $json_result;
?>