3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr = ['key1' => 1, 'key2' => 2]; $tmp = $arr['key1']; $arr['key1'] = $arr['key2']; $arr['key2'] = $tmp; var_dump($arr);;
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.27, 8.4.1 - 8.4.14
array(2) { ["key1"]=> int(2) ["key2"]=> int(1) }
preferences:
151.98 ms | 408 KiB | 5 Q