致命错误：无法访问空属性
我遇到了这个错误，行是这样的：
$stations=$this->$db->query('SELECT * from service_stations');
$db 变量被声明为私有，我在 __construct 函数中使用它，如下所示：
public function __construct() {
//after including the config file
$host=DB_HOST;
$dbname=DB_NAME;
$dbuser=DB_USER;
$dbpsw=DB_PASSWORD;
try{
$pdo_options[PDO::ATTR_ERRMODE]=PDO::ERRMODE_EXCEPTION;
$this->db=new PDO('mysql:host='.$host.';dbname='.$dbname, $dbuser, $dbpsw, $pdo_options);
}
catch(Exception $e)
{
die('Erreur: '.$e->getMessage());
}
}
提前谢谢:)
i have got that error and the line was this :
$stations=$this->$db->query('SELECT * from service_stations');
the $db variable is declared private and i use it in the __construct function like this:
public function __construct() {
//after including the config file
$host=DB_HOST;
$dbname=DB_NAME;
$dbuser=DB_USER;
$dbpsw=DB_PASSWORD;
try{
$pdo_options[PDO::ATTR_ERRMODE]=PDO::ERRMODE_EXCEPTION;
$this->db=new PDO('mysql:host='.$host.';dbname='.$dbname, $dbuser, $dbpsw, $pdo_options);
}
catch(Exception $e)
{
die('Erreur: '.$e->getMessage());
}
}
thx in advance :)
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评论（2）
您可能犯了一个错字：
You have probably made a typo:
您可能想写
$this->db而不是$this->$db。前者访问属性db，后者访问属性，这些名称存储在$db变量中。由于未定义此变量，因此您最终会访问一个空属性，如错误消息所示。You probably meant to write
$this->dbinstead of$this->$db. The former accesses the propertydb, the latter access the property, those name is stored in the$dbvariable. And as this variable is not defined, you end up accessing an empty property, as the error message indicates.