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run code in 500+ PHP versions simultaneously
<?php class Foo { public $id; public function __construct(){ static $counter = 0; $this->id = $counter; ++$counter; } } $collection = [new Foo(), new Foo(), new Foo(), new Foo()]; print_r(array_column($collection, 'id'));

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19.88 ms | 475 KiB | 4 Q