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run code in 300+ PHP versions simultaneously
<?php $arr = array(1); $a =& $arr[0]; //$a and $arr[0] are in the same reference set $arr2 = $arr; //not an assignment-by-reference! $arr2[0]++; var_export($a); echo "\n"; var_export($arr); echo "\n"; var_export($arr2);
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 - 5.6.28, 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 - 8.2.19, 8.3.0 - 8.3.7
2 array ( 0 => 2, ) array ( 0 => 2, )

preferences:
228.77 ms | 406 KiB | 372 Q