PHP：如何输出动态多维数组值？

Question

I have an array like this in PHP:

$array = array(
     'main0' => array(
        'level0' => array('0'=>'value_1'),
        'level1' => array(
               '0' => 'value_2',
               '1' => 'value_3',
               ),
        'level2' => array('0'=>'value_445')
        ),
     'main1' => array(
        'level0' => array('0'=>'value_1'),
        'level1' => array('0'=>'value_12'),
        'level2' => array(
               '0' => 'value_2',
               '1' => 'value_3',
               ),
        'level3' => array('0'=>'value_5')
        ),
);

This array will be dynamic, to many mainkeys and levels, each level also have dynamic amount of values.

My problem is, I'm trying to echo each of the array level in select option html markup. I've tried foreach ($array[][] as $value) but with no luck. How to achieve this in PHP?

EDIT

Solved my problem using 3 foreach, might be not the cleanest solution but it works. My solution in blade php:

<?php $data = Product::GetCategories(); ?>
        @if ($data != null)
            @foreach ($data as $item)
                <optgroup label="{{ $item[0][0] }}">
                    @foreach ($item as $level)
                        @foreach ($level as $v)
                            <option value="{{ $v }}">{{ $v }}</option>
                        @endforeach
                    @endforeach
                </optgroup>
            @endforeach
        @endif

Answer 1

If you don't really care about manipulating the array items, and all you want is to see the result on screen, you may use: print_r($array);

If you do need to do something with the array items, then here is a recursive function(myRecursiveFunction), and a normal function that is executed on a non-array (myNormalFunction) to illustrate the process.

function myRecursiveFunction($array) {
    foreach($array as $key=>$value) {
        if(is_array($value)) {
             myRecursiveFunction($value);
        }
        myNormalFunction($value);
    }
}