PHP-找不到Codeigniter CI_控制器

我不知道怎么了。当我包含在MYC_控制器-CI_控制器中时，它会说：

Fatal error: Class 'CI_Controller' not found in 
/home/vol7_5/byethost3.com/b3_15049873/htdocs/application/core/MYC_Controller.php on line 2

---

在MYC_控制器和前端_控制器的构造函数中，添加

parent:：_construct（）

还有

application/config/congfig.php

中

$config['subclass\u prefix']

的值是多少？subclass\u prefix值是我的_

Fatal error: Class 'CI_Controller' not found in 
/home/vol7_5/byethost3.com/b3_15049873/htdocs/application/core/MYC_Controller.php on line 2

Fatal error: Cannot redeclare class CI_Controller in 
/home/vol7_5/byethost3.com/b3_15049873/htdocs/system/core/Controller.php on line 30