这段php代码为什么没效果？

php

<code> <?php $dbhost='';$dbname='';$dbuser='';$dbpass='';date_default_timezone_set('PRC');try{$pdo=new PDO('mysql:host='.$dbhost.';dbname='.$dbname,$dbuser,$dbpass);}catch(Exception $e){die('sql error');}$pdo->query('SET NAMES utf8');function cd(){global $pdo;return $pdo->lastInsertId();}function qr($var){global $pdo;return $pdo->query($var);}function fo($var){return qr($var)->fetch();}function fa($var){return qr($var)->fetchALL();}$fp=fo('SELECT * FROM post WHERE id='.$p);echo $fp['title'];echo $fp['content'];?>_</code>