3v4l.org

run code in 300+ PHP versions simultaneously
<?php class a { function __toString() { static $i = 0; $a = ['', 'a']; $r = $a[$i]; $i++; return $r; } } $a = new a; var_dump('' === (string)$a and 'a' === (string)$a);
Output for 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 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
bool(true)

preferences:
307.51 ms | 404 KiB | 373 Q