All Nice Templates

The code that I will explain here will display sub categories only when you are viewing a single category which contains sub categories. This template hack is very simple.

Place this code in your category.php file

<?php
if (is_category()) {
$this_category = get_category($cat);
if (get_category_children($this_category->cat_ID) != "") {
echo '<h2>';
single_cat_title();
echo '</h2>';
echo '<ul>';
wp_list_categories('orderby=id&hide_empty=1&show_count=0&title_li=&child_of='.$this_category->cat_ID);
echo '</ul>';
}
}
?>

Put this snippet in your category.php template file and It should show sub categories for your parent categories on category pages.

This code simply does the following:

• Checks whether the current page is a category
• Checks if the category is parent and has sub categories
• If it has sub categories, it displays them with a header and unordered list

Customize the wp_list_categories() function

wp_list_categories('orderby=id&hide_empty=1&show_count=0&title_li=&child_of='.$this_category->cat_ID);

By default it displays categories by ID, hides empty categories, and does not show number of posts within each category.

The following code will show post count besides each category

wp_list_categories('orderby=id&hide_empty=1&show_count=1&title_li=&child_of='.$this_category->cat_ID);

Very easy! You can also change hide_empty=1 to hide_empty=0 to display
empty categories (even if they do not have posts, they appear!)

Source from [ http://mywordpressdesign.com/ ]