3v4l.org

run code in 300+ PHP versions simultaneously
<?php class A {} $a = new A(); $b = new A(); $a->m = $b; $b->m = $a; var_dump(serialize($a));
Output for 8.2.0 - 8.2.18, 8.3.0 - 8.3.7
Deprecated: Creation of dynamic property A::$m is deprecated in /in/svVKT on line 8 Deprecated: Creation of dynamic property A::$m is deprecated in /in/svVKT on line 9 string(44) "O:1:"A":1:{s:1:"m";O:1:"A":1:{s:1:"m";r:1;}}"
Output for 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 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 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
string(44) "O:1:"A":1:{s:1:"m";O:1:"A":1:{s:1:"m";r:1;}}"
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9
string(32) "O:1:"a":1:{s:1:"m";O:1:"a":0:{}}"
preferences:
254.22 ms | 402 KiB | 371 Q