in_category

The timeline below displays how wordpress function in_category has changed across different WordPress versions. If a version is not listed, refer to the next available version below.

WordPress Version: 6.1

/**
 * 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( $single_category ).
 * Prior to v2.7, this function could only be used in the WordPress Loop.
 * As of 2.7, the function can be used anywhere if it is provided a post ID or post object.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.2.0
 * @since 2.7.0 The `$post` parameter was added.
 *
 * @param int|string|int[]|string[] $category Category ID, name, slug, or array of such
 *                                            to check against.
 * @param int|WP_Post               $post     Optional. Post to check. Defaults to the current post.
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    if (empty($category)) {
        return false;
    }
    return has_category($category, $post);
}

WordPress Version: 5.7

/**
 * 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( $single_category ).
 * Prior to v2.7, this function could only be used in the WordPress Loop.
 * As of 2.7, the function can be used anywhere if it is provided a post ID or post object.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.2.0
 * @since 2.7.0 The `$post` parameter was added.
 *
 * @param int|string|int[]|string[] $category Category ID, name, slug, or array of such
 *                                            to check against.
 * @param int|object                $post     Optional. Post to check instead of the current post.
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    if (empty($category)) {
        return false;
    }
    return has_category($category, $post);
}

WordPress Version: 5.5

/**
 * 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( $single_category ).
 * Prior to v2.7, this function could only be used in the WordPress Loop.
 * As of 2.7, the function can be used anywhere if it is provided a post ID or post object.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.2.0
 * @since 2.7.0 The `$post` parameter was added.
 *
 * @param int|string|array $category Category ID, name or slug, or array of said.
 * @param int|object       $post     Optional. Post to check instead of the current post.
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    if (empty($category)) {
        return false;
    }
    return has_category($category, $post);
}

WordPress Version: 5.1

/**
 * 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 {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.2.0
 *
 * @param int|string|array $category Category ID, name or slug, or array of said.
 * @param int|object $post Optional. Post to check instead of the current post. (since 2.7.0)
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    if (empty($category)) {
        return false;
    }
    return has_category($category, $post);
}

WordPress Version: 5.0

/**
 * 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 {@link https://developer.wordpress.org/themes/basics/conditional-tags/ 
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.2.0
 *
 * @param int|string|array $category Category ID, name or slug, or array of said.
 * @param int|object $post Optional. Post to check instead of the current post. (since 2.7.0)
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    if (empty($category)) {
        return false;
    }
    return has_category($category, $post);
}

WordPress Version: 4.7

/**
 * Check 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.
 *
 * @since 1.2.0
 *
 * @param int|string|array $category Category ID, name or slug, or array of said.
 * @param int|object $post Optional. Post to check instead of the current post. (since 2.7.0)
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    if (empty($category)) {
        return false;
    }
    return has_category($category, $post);
}

WordPress Version: 4.1

/**
 * Check if the current post in 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.
 *
 * @since 1.2.0
 *
 * @param int|string|array $category Category ID, name or slug, or array of said.
 * @param int|object $post Optional. Post to check instead of the current post. (since 2.7.0)
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    if (empty($category)) {
        return false;
    }
    return has_category($category, $post);
}

WordPress Version: 7.1

/**
 * Check if the current post in 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.
 *
 * @since 1.2.0
 * @uses has_category()
 *
 * @param int|string|array $category Category ID, name or slug, or array of said.
 * @param int|object $post Optional. Post to check instead of the current post. (since 2.7.0)
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    if (empty($category)) {
        return false;
    }
    return has_category($category, $post);
}

WordPress Version: 3.7

/**
 * Check if the current post in 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.
 *
 * @since 1.2.0
 * @uses has_category()
 *
 * @param int|string|array $category Category ID, name or slug, or array of said.
 * @param int|object $post Optional. Post to check instead of the current post. (since 2.7.0)
 * @return bool True if the current post is in any of the given categories.
 */
function in_category($category, $post = null)
{
    return has_category($category, $post);
}