PHP递归函数有问题吗？

我想在我的第一个和第四个<ol>标记中添加两个不同的类属性，但是我真的不知道如何在递归函数中添加它？有人能帮我吗？

这是我的PHP脚本。

function make_list ($parent = 0, $parent_url = '') {
    global $link;
    echo '<ol>';

    foreach ($parent as $id => $cat) {
        if($cat['parent_id'] == '0'){
            $url = $parent_url . $cat['url'];
            echo '<li><a href="' . $url . '" title="' . $cat['category'] . ' Category Link" style="color: orange; font-weight: bold;">' . $cat['category'] . '</a>';
        } else {
            $url = $parent_url . $cat['url'];
            // Display the item:
            echo '<li><a href="' . $url . '" title="' . $cat['category'] . ' Category Link">' . $cat['category'] . '</a>';
        }

        if (isset($link[$id])) {
            make_list($link[$id], $url);
        }
        echo '</li>';
    }
    echo '</ol>';
}

$mysqli = mysqli_connect("localhost", "root", "", "sitename");
$dbc = mysqli_query($mysqli,"SELECT * FROM categories ORDER BY parent_id, category ASC");
if (!$dbc) {
    print mysqli_error();
}

$link = array();

while (list($id, $parent_id, $category, $url, $depth) = mysqli_fetch_array($dbc)) {
    $link[$parent_id][$id] =  array('parent_id' => $parent_id, 'category' => $category, 'url' => $url, 'depth' => $depth);
}

make_list($link[0]);

输出

<ol>
   <li>First Nested List</li>
   <li>First Nested List</li>
   <li>First Nested List
      <ol>
        <li>Second Nested List</li>
        <li>Second Nested List</li>
        <li>Second Nested List
          <ol>
            <li>Third Nested List</li>
            <li>Third Nested List</li>
            <li>Third Nested List
              <ol>
                <li>Fourth Nested List</li>
                <li>Fourth Nested List</li>
                <li>Fourth Nested List</li>
              </ol>
            </li>
            <li>Third Nested List</li>
            <li>Third Nested List</li>
          </ol>
        </li>
        <li>Second Nested List</li>
        <li>Second Nested List</li>
      </ol>
   </li>
   <li>First Nested List</li>
   <li>First Nested List</li>
</ol>

最佳答案

只需添加深度作为参数即可。然后检查它的0或4还是您需要的任何值。

function make_list ($parent = 0, $parent_url = '', $depth=0) {
...
make_list($link[$id], $url, $depth+1);
...