3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $arr = array('a' => 1, 'b' => 2); foreach($arr as &$k=>$v) $k = strtoupper($k); var_dump($arr);
Output for 5.0.0 - 5.4.32
Fatal error: Key element cannot be a reference in /in/nWRBa on line 4
Process exited with code 255.
Output for 4.4.2 - 4.4.9
Parse error: syntax error, unexpected '&', expecting T_VARIABLE or '$' in /in/nWRBa on line 4
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.4.1
Parse error: parse error, unexpected '&', expecting T_VARIABLE or '$' in /in/nWRBa on line 4
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error, expecting `T_VARIABLE' or `'$'' in /in/nWRBa on line 4
Process exited with code 255.