When making a corporate website, you need to list the corporate product categories in the sidebar of the website. If the company website has many product items, you need to set up secondary categories or subcategories.

How to display subcategories under the current category when building your own website or display subcategories of the category on the article page, especially when making WordPress Chinese themes, you must use this technique.

Method/Steps
1. First, add the following code to the function template function.php of the website theme:

//Display subcategories,
function get_category_root_id($cat)
{
$this_category = get_category($cat); // Get the current category
while($this_category->category_parent) // If the current category has a parent category, loop
{
$this_category = get_category($this_category->category_parent); // Set the current category as the parent category (climb up)
}
return $this_category->term_id; // Return the id number of the root category
}
2. Then paste the following code where you want to display the subcategory on the page (usually in the sidebar)

<?php wp_list_cats(‘child_of=’ . get_category_root_id($cat) . ‘&depth=1&hide_empty=0&hierarchical=1&optioncount=1’);?>
If you want to display the subcategories under the current category more flexibly, you can use the following code:

<?php
$args=array(
‘child_of’=> get_category_root_id($cat),
‘hide_empty’=>’0’,
);
$categories=get_categories($args);
foreach($categories as $category) {
echo ‘<h3><a href=”‘%20.%20get_category_link(%20$category->term_id%20)%20.%20′” title=”‘ . sprintf( __( “View all posts in %s” ), $category->name ) . ‘” ‘ . ‘>’ . $category->name.'</a></h3>’;
}
?>