3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array1 = [0, 1]; $array2 = [&$array1]; ob_start(function($str) use(&$array1) { static $i = 0; if ($i++ == 4) { unset($array1[0]); //unset($array1[1]); } return "$i: $str"; }, 1); var_dump($array2);
Output for 7.1.0 - 7.1.20, 7.2.6 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
1: array(1) { 2: [0]=> 3: 4: &array(2) { 5: [0]=> 6: 7: int(0) 8: [1]=> 9: 10: int(1) 11: 12: } 13: } 14:
Output for 7.0.0 - 7.0.24
1: array(1) { 2: [0]=> 3: 4: &array(2) { 5: [0]=> 6: 7: UNKNOWN:0 8: [1]=> 9: 10: int(1) 11: 12: } 13: } 14:
Output for 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.30
1: array(1) { 2: [0]=> 3: 4: &array(2) { 5: [0]=> 6: 7: string(4) "8: 1a9: " 10: [1]=> 11: 12: int(1) 13: 14: } 15: } 16:
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29
Parse error: syntax error, unexpected '[' in /in/sKusd on line 3
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.3.11, 4.4.0 - 4.4.1, 5.0.0 - 5.0.5
Parse error: parse error, unexpected '[' in /in/sKusd on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/sKusd on line 3
Process exited with code 255.

preferences:
263.24 ms | 401 KiB | 378 Q