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run code in 200+ php & hhvm versions
Bugs & Features
<?php $a = [100 => 'foo']; $b = [100 => 'bar']; var_dump(array_merge($a, $b)); var_dump($a + $b);
based on oWAoN
Output for 5.6.0 - 5.6.30, hhvm-3.15.4, 7.0.0 - 7.3.0beta1
array(2) { [0]=> string(3) "foo" [1]=> string(3) "bar" } array(1) { [100]=> string(3) "foo" }