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<?php $a = []; $a[] = $a; echo "\na: ".serialize($a); $b = []; $b[] =& $b; echo "\nb: ".serialize($b); $c = new stdClass(); $c->c = $c; echo "\nc: ".serialize($c); $d = new stdClass(); $d->c =& $d; echo "\nd: ".serialize($d); $e = new stdClass(); $e->e = clone $e; echo "\ne: ".serialize($e);
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 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.26, 8.4.1 - 8.4.13
a: a:1:{i:0;a:0:{}} b: a:1:{i:0;a:1:{i:0;R:2;}} c: O:8:"stdClass":1:{s:1:"c";r:1;} d: O:8:"stdClass":1:{s:1:"c";R:1;} e: O:8:"stdClass":1:{s:1:"e";O:8:"stdClass":0:{}}

preferences:
175.28 ms | 408 KiB | 5 Q