Question

How can I return multidimensional array keys in tree format in PHP?

For example, if I have the following array:

$array = array ( 
    array (
        'name' => 'A', 
        'product' => array (
            'qty' => 1,
            'brand' => 'Tim'
        ), 
        'goods' => array (
            'qty' => 2
        ), 
        'brand' => 'Lin'
    ),
    array (
        'name' => 'B', 
        'product' => array (
            'qty' => 6,
            'brand' => 'Coff'
        ),
        'goods' => array (
            'qty' => 4
        ), 
        'brand' => 'Ji'
    )
);

How can I get a result like the following — including no repeating of keys:

-name
-product
--qty
--brand
-goods
--qty
--brand

Answer 1

With an unlimited depth you need a recursive function. I suppose you have the parents in $names and the childs in $children:

function render_select($root=0, $level=-1) 
{
    global $names, $children;
    if ($root != 0)
       echo '<option>' . strrep(' ', $level) . $names[$root] . '</option>';
    foreach ($children[$root] as $child)
       render_select($child, $level+1);
}

This functions use useful because you can feed it with 2 variables. The other answere requires a multidimensional array.