PHP - 如何确定子数组的父项数？

Question

I'm not so strong with arrays but I need to determine how to count the number of parents a child array has in order to determine the indenting to display it as an option in a SELECT.

So, if I have this array:

array(
      'World'=>array(
            'North America'=>array(
                  'Canada'=>array(
                       'City'=>'Toronto'
                   )
            )
      )
);

How would I go about determining how many parents 'City' has in order to translate that into the number of spaces I want to use as an indent?

Thanks for any help.

EDIT: Let's see if I can explain myself better:

I have this code I'm using to build the OPTIONS list for a SELECT:

function toOptions($array) {

    foreach ($array as $key=>$value) {
        $html .= "<option value=\"" . $key . "\" >";

        $html .=  $value['title'];

        $html .= "</option>";

        if (array_key_exists('children', $value)) {
            $html .= toOptions($value['children']);
        }

    }

    return $html;

}

print toOptions($list);

So, I'm trying to determine how to get the number of parents in order to add spaces before the title in this line:

$html .=  $value['title'];

Like:

$html .= "   " . $value['title'];

But, I'm not sure how to figure out how many spaces to add.

Hopefully this is more clear.

Thanks for any help so far.

Answer 1

$x = array(
      'World'=>array(
            'North America'=>array(
                  'Canada'=>array(
                       'City'=>'Toronto'
                   )
            )
      )
);

// This function do something with the key you've found in the array
function visit($name, $depth)
{
    echo $name . ' has ' . $depth . ' parents.'; 
}

// This function visits all the contents aff $array
function find_recursive($array, $depth = 0)
{
    if (is_array($array)) {
        foreach ($array as $k => $value) {
            visit($k, $depth + 1);
            find_recursive($array, $depth + 1);
        }
    }
}

For visiting:

find_recursive($x);