How to build multi level navigation with PHP - php

Question

Im working on a prototype, and would like to build a multi level navigation - however not by looping through an array. I have a $depth and a $children, which should determine the depth of the navigation and the number of children on each level. So $depth = 4, $children = 8 would yield 4096 menu items.
This is a snippet af the output I would like:
<ul>
<li class="level-1">
Subject 1
<ul>
<li class="level-2">
Subject 1.1
<ul>
<li class="level-3">
Subject 1.1.1
</li>
...
</ul>
</li>
...
</ul>
</li>
...
</ul>
So far I have tried this, but I cant get my head around it :(
function draw_list ($depth, $children) {
echo '<ul>';
for ($i = 0; $i < $children; $i++) {
echo '<li>' . ($i++);
$depth--;
if ($depth > 0) {
echo draw_list($depth, $children);
}
echo '</li>';
}
echo '</ul>';
}

Answer 1

Several things required as I see it...
The $depth--; needs to be outside of the for loop
You were incrementing $i twice, once in the for statement, and then again on the echo '<li>' . ($i++);
The $depth check was stopping one early, so make >= instead of just > (Edit, thinking about it, this is an incorrect statement)
That should give you...
function draw_list ($depth, $children) {
echo '<ul>';
$depth--;
for ($i = 0; $i < $children; $i++) {
echo '<li>' . $i;
if ($depth > 0) {
echo draw_list($depth, $children);
}
echo '</li>';
}
echo '</ul>';
}
Update
For the display of the level numbering, try passing a string value through as a parameter...
function draw_list ($depth, $children, $display=''){
echo '<ul>';
$depth--;
for ($i = 0; $i < $children; $i++) {
echo '<li>' . $display . ($i + 1);
if ($depth > 0) {
echo draw_list($depth, $children, $display . ($i + 1) . '.');
}
echo '</li>';
}
echo '</ul>';
}

Answer 2

I ended up doing this:
function build_nav ($depth, $children, $levels = array()) {
echo '<ul>';
$depth--;
for ($i = 0; $i < $children; $i++) {
$levels[$depth] = $i+1;
echo '<li>';
echo 'Subject: ' . implode('.', $levels);
if ($depth > 0) {
build_nav($depth, $children, $levels);
}
echo '</li>';
}
echo '</ul>';
}