Description:
------------
I noticed when I extract the keys of an array using array_keys, if a key is an string with a number, on the resulting array from the array_keys execution I get an integer for this key instead of a string.

My version of PHP is 5.3.5-1ubuntu7.3.

Regards!

Test script:
---------------
$a = array(
	'1' => 'apple',
	'2' => 'banana',
	'3' => 'orange',
	'4' => 'stawberry',
);
$keys = array_keys($a);
echo gettype( $keys[0] );

Expected result:
----------------
Output:

string

Actual result:
--------------
Output

integer