3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php $arr = [ 'USA' => [ 'Alabama' => [ 'Montgomery', 'Birmingham' ], 'Arizona' => [ 'Phoenix', 'Mesa', 'Gilbert' ] ], 'Germany' => [ 'West Germany' => [ 'Bonn', 'Cologne' ] ] ]; $iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($arr)); $keys = array(); foreach ($iterator as $key => $value) { // Build long key name based on parent keys for ($i = $iterator->getDepth() - 1; $i >= 0; $i--) { $key = $iterator->getSubIterator($i)->key() . '_' . $key; } $keys[] = $key; } var_export($keys);
Output for 5.4.0 - 7.2.0
array ( 0 => 'USA_Alabama_0', 1 => 'USA_Alabama_1', 2 => 'USA_Arizona_0', 3 => 'USA_Arizona_1', 4 => 'USA_Arizona_2', 5 => 'Germany_West Germany_0', 6 => 'Germany_West Germany_1', )
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.3.29
Parse error: syntax error, unexpected '[' in /in/gtChH on line 2
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.4.1, 5.0.0 - 5.0.5
Parse error: parse error, unexpected '[' in /in/gtChH on line 2
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/gtChH on line 2
Process exited with code 255.