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run code in 300+ PHP versions simultaneously
<?php $A = array(3,4); $B = &$A[0]; //$F = &$A[1]; $C = $A; $D = $A; debug_zval_dump($C); debug_zval_dump($D); $C[0] = $D[1]; debug_zval_dump($C); debug_zval_dump($D); $C[0] = 10; $D[1] = 20; echo $A[0] . ' ' . $A[1];
Output for 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
array(2) refcount(4){ [0]=> reference refcount(2) { int(3) } [1]=> int(4) } array(2) refcount(4){ [0]=> reference refcount(2) { int(3) } [1]=> int(4) } array(2) refcount(2){ [0]=> reference refcount(3) { int(4) } [1]=> int(4) } array(2) refcount(3){ [0]=> reference refcount(3) { int(4) } [1]=> int(4) } 10 4
Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30
array(2) refcount(4){ [0]=> &int(3) [1]=> int(4) } array(2) refcount(4){ [0]=> &int(3) [1]=> int(4) } array(2) refcount(2){ [0]=> &int(4) [1]=> int(4) } array(2) refcount(3){ [0]=> &int(4) [1]=> int(4) } 10 4
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 - 5.6.38
array(2) refcount(4){ [0]=> &long(3) refcount(2) [1]=> long(4) refcount(1) } array(2) refcount(4){ [0]=> &long(3) refcount(2) [1]=> long(4) refcount(1) } array(2) refcount(2){ [0]=> &long(4) refcount(3) [1]=> long(4) refcount(2) } array(2) refcount(3){ [0]=> &long(4) refcount(3) [1]=> long(4) refcount(2) } 10 4

preferences:
301.77 ms | 404 KiB | 449 Q