Online PHP editor | refs for lsXp5

<?php $array = array(); echo PHP_EOL . ' on empty array: ' . PHP_EOL; var_dump(key($array)); $array[] = 'f'; echo PHP_EOL . ' size one array: ' . PHP_EOL; var_dump(key($array)); $array[] = 'f'; echo PHP_EOL . ' size two array: ' . PHP_EOL; var_dump(key($array)); echo PHP_EOL . ' within loop: ' . PHP_EOL; foreach ($array as $item) { var_dump(key($array)); } echo PHP_EOL . ' after loop: ' . PHP_EOL; var_dump(key($array)); reset($array); echo PHP_EOL . ' after reset: ' . PHP_EOL; var_dump(key($array)); end($array); echo PHP_EOL . ' after end: ' . PHP_EOL; var_dump(key($array)); echo PHP_EOL . ' trying to trigger "Undefined index: " error: with NULL key' . PHP_EOL; $array[null]; echo PHP_EOL . ' trying to trigger "Undefined index: " error: with empty string key' . PHP_EOL; $array[''];