in_category ( $category, $post = null )
- (int|string|array) category Category ID, name or slug, or array of said.
- (int|object) post Optional. Post to check instead of the current post. (since 2.7.0)
- (bool) True if the current post is in any of the given categories.
- Introduced in WordPress: 1.2.0
- Deprecated in WordPress: —
Checks if the current post is within any of the given categories.The given categories are checked against the post's categories' term_ids, names and slugs.
Categories given as integers will only be checked against the post's categories' term_ids.
Prior to v2.5 of WordPress, category names were not supported.
Prior to v2.7, category slugs were not supported.
Prior to v2.7, only one category could be compared: in_category( $single_category ).
Prior to v2.7, this function could only be used in the WordPress Loop.
As of 2.7, the function can be used anywhere if it is provided a post ID or post object.
For more information on this and similar theme functions, check out
the [Conditional Tags](https://developer.wordpress.org/themes/basics/conditional-tags/) article in the Theme Developer Handbook.