How to construct a nested associative array

Question

I am trying to construct a deeply nested associative array but i don't know what the rules are in constructing one.I have this theoritical array:

-one
-two
-three
-four
    -one
    -two
    -three
    -four
-five
-six
-seven
-eight
-nine
    -one
    -two            
    -three 
            -one
            -two
            -three
            -four
            -five
            -six

and i made this attempt at representing that as a php associative array;

$associative = array(
'one' => 'one-1',
'two' => 'two-2',
'three' => 'three-3',
'four' => 'four-4'
(
    'one' => 'one-four-1',
    'two' => 'two-four-2',
    'three' => 'three-four-3',
    'four' => 'four-four-4'
)
'five' => 'five-5',
'six' => 'six-6',
'seven' => 'seven-7',
'eight' => 'eight-8',
'nine' => 'nine-9'
(
    'one' => 'one-nine-1',
    'two' => 'two-nine-2',          
    'three' => 'three-nine-3' 
(   
        'one' => 'one-nine-three-1',
        'two' => 'two-nine-three-2',
        'three' => 'three-nine-three-3',
        'four' => 'four-nine-three-4',
        'five' => 'five-nine-three-5',
        'six' => 'six-nine-three-6'
))
);
$keys = array_values($associative);
echo $keys[0];

When i try executing the php snippet i get this error;

Parse error: syntax error, unexpected '(', expecting ')' in C:\wamp\www\array.php on line 7

So my question is,what is the correct way of writing such an array and what rule should i follow when i wish to add more children?.

Note:In my theoritical array,four has four children,nine has three children and three has six children.Anyway,i hope the idea of having children is understood in my dummy array.

Answer 1

The subarrays are actual values of your top-level array elements, and you have to initiate them using array() as well:

$associative = array(
    'one' => 'one-1',
    'two' => 'two-2',
    'three' => 'three-3',
    'four' => array(
        'one' => 'one-four-1',
        'two' => 'two-four-2',
        'three' => 'three-four-3',
        'four' => 'four-four-4'
    ),
    'five' => 'five-5',
    'six' => 'six-6',
    'seven' => 'seven-7',
    'eight' => 'eight-8',
    'nine' => array(
        'one' => 'one-nine-1',
        'two' => 'two-nine-2',          
        'three' => array(   
            'one' => 'one-nine-three-1',
            'two' => 'two-nine-three-2',
            'three' => 'three-nine-three-3',
            'four' => 'four-nine-three-4',
            'five' => 'five-nine-three-5',
            'six' => 'six-nine-three-6'
        ),
    ),
);

Note that I also added ,s after each closing ), because, like I said, the arrays are values of the parent array elements.

Answer 2

$associative = array(
  'one' => 'one-1',
  'two' => 'two-2',
 'three' => 'three-3',
 'four' => array(
   'one' => 'one-four-1',
    'two' => 'two-four-2',
    'three' => 'three-four-3',
   'four' => 'four-four-4'
 ),
  'five' => 'five-5',
  'six' => 'six-6',
  'seven' => 'seven-7',
  'eight' => 'eight-8',
  'nine' => array(
    'one' => 'one-nine-1',
    'two' => 'two-nine-2',          
    'three' => array(
        'one' => 'one-nine-three-1',
        'two' => 'two-nine-three-2',
        'three' => 'three-nine-three-3',
        'four' => 'four-nine-three-4',
        'five' => 'five-nine-three-5',
        'six' => 'six-nine-three-6'
    )
  )
);
print_r($associative);