How to get category tree structure in Magento programatically ?

In many places we will need to get the category tree in magento programmatically. With the below peace of code you can get the tree anywhere in magento



   $rootCatId = Mage::app()->getStore()->getRootCategoryId(); // it will fetch your current store root id
   $catlistHtml = getTreeCategories($rootCatId, false);
   echo $catlistHtml;

function getTreeCategories($parentId, $isChild){
    $allCats = Mage::getModel('catalog/category')->getCollection()
                ->addAttributeToSelect('*')
                ->addAttributeToFilter('is_active','1')  // is acategory active
                ->addAttributeToFilter('include_in_menu','1') //  to check include_in_menu yes or no
                ->addAttributeToFilter('parent_id',array('eq' => $parentId))  // filter parent id
                ->addAttributeToSort('position', 'asc');
              
    $class = ($isChild) ? "sub-cat-list" : "cat-list";
    $html .= '<ul class="'.$class.'">';
    foreach($allCats as $category)
    {
        $html .= '<li><span>'.$category->getName()."</span>";
        $subcats = $category->getChildren();
        if($subcats != ''){
            $html .= getTreeCategories($category->getId(), true);
        }
        $html .= '</li>';
    }
    $html .= '</ul>';
    return $html;
}


Please let me know if there is other such easy way to do this.I will love to hear and update my post.

thanks