<?
class A{}
$arr = [];
for($i = 0;$i<5;$i++) {
        $obj = new A;
        $obj->id = $i;
        $arr[] = &$obj;

        unset($obj);
    }
    print_r($arr);
    $arr1 = [];
    for($i = 0; $i < 5; $i++)
    {
        $object = new A();
        $object->property1 = $i;
        //$object->property2 = true;
        //$object->property3 = 'Str';

        $arr1[] = &$object; //reference

    }
    print_r($arr1);