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<?php // Adapted from last example on http://nikic.github.io/2015/05/05/Internal-value-representation-in-PHP-7-part-1 $a = array(); // $a -> zend_array_1(refcount=1, value=[]) $b = $a; // $a, $b, -> zend_array_1(refcount=2, value=[]) $c = $b; // $a, $b, $c -> zend_array_1(refcount=3, value=[]) $x = $c; // $a, $b, $c, $x -> zend_array_1(refcount=4, value=[]) $d =& $c; $y =& $d; // $a, $b, $x -> zend_array_1(refcount=4, value=[]) // $c, $d, $y -> zend_reference_1(refcount=3) ---^ echo "Before\n"; debug_zval_dump($a); debug_zval_dump($b); debug_zval_dump($c); debug_zval_dump($d); $d[] = 1; // $a, $b, $x -> zend_array_1(refcount=3, value=[]) // $c, $d, $y -> zend_reference_1(refcount=3) -> zend_array_2(refcount=1, value=[1]) echo "After\n"; debug_zval_dump($a); debug_zval_dump($b); debug_zval_dump($c); debug_zval_dump($d);
Output for 8.4.1 - 8.4.12
Before array(0) interned { } array(0) interned { } array(0) interned { } array(0) interned { } After array(0) interned { } array(0) interned { } array(1) packed refcount(2){ [0]=> int(1) } array(1) packed refcount(2){ [0]=> int(1) }
Output for 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25
Before array(0) interned { } array(0) interned { } array(0) interned { } array(0) interned { } After array(0) interned { } array(0) interned { } array(1) refcount(2){ [0]=> int(1) } array(1) refcount(2){ [0]=> int(1) }
Output for 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30
Before array(0) refcount(1){ } array(0) refcount(1){ } array(0) refcount(1){ } array(0) refcount(1){ } After array(0) refcount(1){ } array(0) refcount(1){ } array(1) refcount(2){ [0]=> int(1) } array(1) refcount(2){ [0]=> int(1) }
Output for 7.1.0 - 7.1.33, 7.2.0 - 7.2.33
Before array(0) refcount(6){ } array(0) refcount(6){ } array(0) refcount(6){ } array(0) refcount(6){ } After array(0) refcount(5){ } array(0) refcount(5){ } array(1) refcount(2){ [0]=> int(1) } array(1) refcount(2){ [0]=> int(1) }
Output for 7.0.0 - 7.0.33
Before array(0) refcount(5){ } array(0) refcount(5){ } array(0) refcount(5){ } array(0) refcount(5){ } After array(0) refcount(4){ } array(0) refcount(4){ } array(1) refcount(2){ [0]=> int(1) } array(1) refcount(2){ [0]=> int(1) }
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40
Before array(0) refcount(4){ } array(0) refcount(4){ } array(0) refcount(1){ } array(0) refcount(1){ } After array(0) refcount(4){ } array(0) refcount(4){ } array(1) refcount(1){ [0]=> long(1) refcount(2) } array(1) refcount(1){ [0]=> long(1) refcount(2) }

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151.51 ms | 416 KiB | 5 Q