什么情况directory_separator？

define(\'PHPCMS_PATH\', dirname(__FILE__).DIRECTORY_SEPARATOR);//定义常量

include PHPCMS_PATH.\'/phpcms/base.php\';//引入文件

//pc_base::creat_app();

$db_config = pc_base::load_config(\'database\');//调用pc_base类里的load_config方法directory_separator，下面三个一样

pc_base::load_sys_class(\'mysql\', \'\', 0);

pc_base::load_sys_class(\'param\', \'\', 0);

pc_base::load_model(\'content_model\');

$db=new mysql();//实例化类mysl,下面这些是这个类里面的方法

$db->open($db_config[\'default\']);

$pre=$db_config[\'default\'][\'tablepre\'];

$db->connect();

$cates=$db->select(\'`catid` as cid,`parentid` as pid,`catname` as cname\',\"{$pre}category\",\"type=0 and child=0\");

zend框架提示如下错误是怎么回事 - 技术问答

3# 我把他删除了directory_separator，还是提示错误 Fatal error: Uncaught exception \\\'Zend_Db_Adapter_Exception\\\' with message \\\'The PDO extension is required for this adapter but the extension is not loaded\\\' in E:\\\\AppServ\\\\}