Output HTML Tree With Array - php

Question

Is there a more elegant way to output the given html structure with an array? I found some recursive solutions but therefore a parent_id is needed (if I understand correctly).
HTML
<ul>
<li>Level 1</li>
<li>
<ul>
<li>Level 2</li>
<li>
<ul>
<li>Level 3</li>
</ul>
</li>
</ul>
</li>
</ul>
Array
Array
(
[0] => Level 1
[1] => Array
(
[0] => Level 2
[1] => Array
(
[0] => Level 3
)
)
)
Loops
<ul>
<?php foreach($array as $arr) : ?>
<li>
<?php if(is_array($arr)) : ?>
<ul>
<?php foreach($arr as $a) : ?>
<li>
<?php if(is_array($a)) : ?>
<ul>
<?php foreach($a as $aa) : ?>
<li><?php echo $aa; ?></li>
<?php endforeach; ?>
</ul>
<?php else : ?>
<?php echo $a; ?>
<?php endif; ?>
</li>
<?php endforeach; ?>
</ul>
<?php else : ?>
<?php echo $arr; ?>
<?php endif; ?>
</li>
<?php endforeach; ?>
</ul>
I´m a bit worried about the performance of this approach :-D

Answer 1

do it just recursive:
<?PHP
function doOutputList($TreeArray)
{
echo '<ul>';
foreach($TreeArray as $arr)
{
echo '<li>';
if(is_array($arr))
{
doOutputList($arr);
}
else
{
echo $arr;
}
echo '</li>';
}
echo '</ul>';
}
doOutputList($array);
?>
Or if you like good readable HTML Code try this:
<?PHP
function doOutputList($TreeArray, $deep=0)
{
$padding = str_repeat(' ', $deep*3);
echo $padding . "<ul>\n";
foreach($TreeArray as $arr)
{
echo $padding . " <li>\n";
if(is_array($arr))
{
doOutputList($arr, $deep+1);
}
else
{
echo $padding .' '. $arr;
}
echo $padding . " </li>\n";
}
echo $padding . "</ul>\n";
}
doOutputList($array);
?>