PHP array_slice not returning array with integer keys

Question

Say, I've got the following code in PHP:
included_file.php:

DEFINE("MSWFFN",serialize(array(
  "mnu"=>array("n"=>"topmnu.swf","w"=>"980px","h"=>"80px","i"=>"mnu","p"=>"&subp=home")
)));

main_file.php:

require_once("included_file.php");
global $MSWFFN;
$MSWFFN=unserialize(MSWFFN);
$swf=array_slice($MSWFFN,0,1,false); //first swf from cfg
var_dump($MSWFFN);
var_dump($swf);

Based on what's said [in this question][1] and on the [php website][2] it should return an array with integer keys, but it does not.
Any idea on why does it not change the 'mnu' key to 0?
Output:

array (size=1)
  'mnu' => 
    array (size=5)
      'n' => string 'topmnu.swf' (length=10)
      'w' => string '980px' (length=5)
      'h' => string '80px' (length=4)
      'i' => string 'mnu' (length=3)
      'p' => string '&subp=home' (length=10)

array (size=1)
  'mnu' => 
    array (size=5)
      'n' => string 'topmnu.swf' (length=10)
      'w' => string '980px' (length=5)
      'h' => string '80px' (length=4)
      'i' => string 'mnu' (length=3)
      'p' => string '&subp=home' (length=10)

Oh, btw my Apache Version is Apache/2.2.23 (Win32) PHP/5.3.18 (VertrigoServ v2.29) [1]: PHP: Get n-th item of an associative array [2]: https://www.php.net/manual/en/function.array-slice.php

Answer 1

You are not using numeric keys.

Note that array_slice() will reorder and reset the numeric array indices by default. You can change this behaviour by setting preserve_keys to TRUE.

There's even a 10-year-old comment regarding this "surprise".

Also, for what it's worth, your output of the original variable and the output of array_slice() is exactly the same, making the latter a bit useless.

Answer 2

To accomplish that, you can use array_values():

var_dump(array_values($MSWFFN));

Output:

Array (
    [0] => Array
        (
            [n] => topmnu.swf
            [w] => 980px
            [h] => 80px
            [i] => mnu
            [p] => &subp=home
        )

    )