3v4l.org

run code in 500+ PHP versions simultaneously
<?php $x = ''; $x[3] = 'foo'; var_dump(gettype($x)); var_export($x);
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
Warning: Only the first byte will be assigned to the string offset in /in/DfQsu on line 4 string(6) "string" ' f'
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
string(6) "string" ' f'
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 - 5.6.40, 7.0.0 - 7.0.33
string(5) "array" array ( 3 => 'foo', )

preferences:
104.14 ms | 2635 KiB | 4 Q