json object array 对象 数组 json_encode 有大用 有大大用

<?php
$json = '{"userFriendId":"%s", "friendId":"%s", "friendEmail":"%s", "groupId":"%s", "groupName":"%s"}';
echo sprintf($json, $userFriendId, $friendId, $friendEmail, $groupId, htmlspecialchars($groupName));
?>