3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php var_dump(reset(array_flip(array('foo' => 'bar'))));
Output for 7.0.0 - 7.3.0rc3
Notice: Only variables should be passed by reference in /in/MHVov on line 2 string(3) "foo"
Output for 4.3.0 - 5.0.4, hhvm-3.10.1 - 3.17.3
string(3) "foo"
Output for 5.1.0 - 5.6.30
Strict Standards: Only variables should be passed by reference in /in/MHVov on line 2 string(3) "foo"
Output for 5.0.5
Fatal error: Only variables can be passed by reference in /in/MHVov on line 2
Process exited with code 255.