3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = array('1'=>'a1','2'=>'a2'); $b = array('2'=>'b2'); var_dump($a+$b); var_dump($b+$a); var_dump(array_merge($a,$b)); var_dump(array_merge($b,$a));
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 - 8.3.4, 8.3.6
array(2) { [1]=> string(2) "a1" [2]=> string(2) "a2" } array(2) { [2]=> string(2) "b2" [1]=> string(2) "a1" } array(3) { [0]=> string(2) "a1" [1]=> string(2) "a2" [2]=> string(2) "b2" } array(3) { [0]=> string(2) "b2" [1]=> string(2) "a1" [2]=> string(2) "a2" }
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 array(2) { [1]=> string(2) "a1" [2]=> string(2) "a2" } array(2) { [2]=> string(2) "b2" [1]=> string(2) "a1" } array(3) { [0]=> string(2) "a1" [1]=> string(2) "a2" [2]=> string(2) "b2" } array(3) { [0]=> string(2) "b2" [1]=> string(2) "a1" [2]=> string(2) "a2" }

preferences:
174.46 ms | 402 KiB | 186 Q