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<?php $c = ['t1' => null, 't2' => 2]; $a= isset($c['t1']); isset($c['t11']) & var_dump('test'); var_dump(isset($sdad)); die; abstract class T { static public $instanses; final private function __construct(){ } public static function getInstance() { if (!(static::$instanses instanceof static)) { static::$instanses = new static; } return static::$instanses; } } class A extends T { static public $instanses; } class B extends A { static public $instanses; } $t = A::getInstance(); var_dump($t); $t1 = B::getInstance(); var_dump($t1); new B(); ?>
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.7
string(4) "test" bool(false)
preferences:
166.8 ms | 404 KiB | 199 Q