array_values() returns an array of all values of an associative array.

<?PHP
	$arr=array("apple"=>"carbon","rice"=>"carbon","nuts"=>"fat","meat"=>"protein");
    $arr2=array_values($arr);
	foreach($arr2 as $element) echo "$element, "; //carbon, carbon, fat, protein, 
?>

If the parameter array is empty, return an empty array. If the parameter is not an associative array, report ERROR.

<?PHP
	$arr = array();
    $elem = array_values($arr);
    print_r ($elem);
	
	//the result is:
	Array
	(
	)	
?>

array_keys() retrieves all keys of an associative array.

<?PHP
	$arr=array("apple"=>"carbon","rice"=>"carbon","nuts"=>"fat","meat"=>"protein");
    $arr2=array_keys($arr);
	foreach($arr2 as $element) echo "$element, "; //apple, rice, nuts, meat, 
?>