3v4l.org

run code in 300+ PHP versions simultaneously
<?php $var=''; print_r(isset($var)); var_dump($var); $var[0]='l'; var_dump($var);
Output for 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, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
1string(0) "" string(1) "l"
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20
1string(0) "" array(1) { [0]=> string(1) "l" }
preferences:
190.12 ms | 402 KiB | 212 Q