note 129853 added to function.array-keys

PHP arrays are weird. So the result of <?php $array = [ 'element0', 'element1' => 'Hello World', 'element2' => 42, 'element3' => [ 'aaa', 'bbb' ], ]; print_r( array_keys($array) ); ?> is a surprising though correct Array ( [0] => 0 [1] => element1 [2] => element2 [3] => element3 ) Arrays in php are really ordered key value pairs where if a value is missing it will become a value with a number as key. To get the intuitive first dimension of an array use a map with function to determine if a key is in fact an index. This <?php $array_first = array_map( fn ($key)=> is_int($key)?$array[$key]:$key , array_keys($array) ); print_r($array_first); ?> will show Array ( [0] => element0 [1] => element1 [2] => element2 [3] => element3 ) However in a niche case <?php $array = [ 'element0', 'element1' => 'Hello World', 'element2' => 42, 'element3' => [ 'aaa', 'bbb' ], 12 => 'I\'m a field, not a key' ]; ?> this won't work of course and output Array ( [0] => element0 [1] => element1 [2] => element2 [3] => element3 [4] => I'm a field, not a key ) ---- Server IP: 45.112.84.4 Probable Submitter: 80.90.5.137 (proxied: 83.97.87.43) ---- Manual Page -- https://php.net/manual/en/function.array-keys.php Edit -- https://main.php.net/note/edit/129853 Del: integrated -- https://main.php.net/note/delete/129853/integrated Del: useless -- https://main.php.net/note/delete/129853/useless Del: bad code -- https://main.php.net/note/delete/129853/bad+code Del: spam -- https://main.php.net/note/delete/129853/spam Del: non-english -- https://main.php.net/note/delete/129853/non-english Del: in docs -- https://main.php.net/note/delete/129853/in+docs Del: other reasons-- https://main.php.net/note/delete/129853 Reject -- https://main.php.net/note/reject/129853 Search -- https://main.php.net/manage/user-notes.php