This Conditional Tag Check if a category is an ancestor of another category. This is a boolean function, meaning it returns either TRUE or FALSE.
<?php cat_is_ancestor_of( $cat1, $cat2 ); ?>
This example, placed in a theme's archive.php, uses Conditional Tags to show different content depending on the category being displayed. This is helpful when it is necessary to include something for any child category of a given category, instead of using category-slug.php method where you'd have to create category-slug.php files for each and every category.
The code snip below checks to see if the category called 'Music' (ID 4) is being processed, and if so, presents a wp_nav_menu for the Music archive page, and any subcategories of Music (e.g. jazz, classical.)
<?php // if the category is music or a music SUBcategory, if (cat_is_ancestor_of(4, $cat) or is_category(4)): ?> <div id="music_subnav_menu" class="subnav_menu"> <?php wp_nav_menu( array('menu' => 'Music' )); ?> </div> <?php endif; ?>
cat_is_ancestor_of() is located in