从 PHP 中的空值创建默认对象?

I see this error only after upgrading my PHP environment to PHP 5.4 and beyond. The error points to this line of code:

Error:

Creating default object from empty value

Code:

$res->success = false;

Do I first need to declare my $res object?

解决方案

Your new environment may have E_STRICT warnings enabled in error_reporting for PHP versions <= 5.3.x, or simply have error_reporting set to at least E_WARNING with PHP versions >= 5.4. That error is triggered when $res is NULL or not yet initialized:

$res = NULL;
$res->success = false; // Warning: Creating default object from empty value

PHP will report a different error message if $res is already initialized to some value but is not an object:

$res = 33;
$res->success = false; // Warning: Attempt to assign property of non-object

In order to comply with E_STRICT standards prior to PHP 5.4, or the normal E_WARNING error level in PHP >= 5.4, assuming you are trying to create a generic object and assign the property success, you need to declare $res as an object of stdClass in the global namespace:

$res = new stdClass();
$res->success = false;