Linkify Categories

Author:Scott Reilly
First released:2009-06-12
Last update:2015-08-13
Compatibility:WP 2.8 – 4.3.1
Download:[ zip ]

Turn a string, list, or array of category IDs and/or slugs into a list of links to those categories.

Extended Description

The plugin provides a widget called “Linkify Catagories” as well as a template tag, c2c_linkify_categories(), which allow you to easily specify categories to list and how to list them. Categories are specified by either ID or slug. See other parts of the documentation for example usage and capabilities.

Links: Plugin Homepage | Plugin Directory Page | Author Homepage

Find out more at the plugin’s WordPress Plugin Repository page.


Click to see full-size image.

  1. linkify-categories screenshot 1

    The plugin’s widget configuration.


  1. Unzip inside the /wp-content/plugins/ directory for your site (or install via the built-in WordPress plugin installer)
  2. Activate the plugin through the ‘Plugins’ admin menu in WordPress
  3. Use the c2c_linkify_categories() template tag in one of your templates (be sure to pass it at least the first argument indicating what category IDs and/or slugs to linkify — the argument can be an array, a space-separate list, or a comma-separated list). Other optional arguments are available to customize the output.

Template Tags

The plugin provides one template tag for use in your theme templates, functions.php, or plugins.


  • <?php c2c_linkify_categories( $categories, $before = '', $after = '', $between = ', ', $before_last = '', $none = '' ) ?>
    Displays links to each of any number of categories specified via category IDs/slugs


  • $categories
    A single category ID/slug, or multiple category IDs/slugs defined via an array, or multiple categories IDs/slugs defined via a comma-separated and/or space-separated string

  • $before
    (optional) To appear before the entire category listing (if categories exist or if ‘none’ setting is specified)

  • $after
    (optional) To appear after the entire category listing (if categories exist or if ‘none’ setting is specified)

  • $between
    (optional) To appear between categories

  • $before_last
    (optional) To appear between the second-to-last and last element, if not specified, ‘between’ value is used

  • $none
    (optional) To appear when no categories have been found. If blank, then the entire function doesn’t display anything


  • These are all valid calls:
<?php c2c_linkify_categories(43); ?>
<?php c2c_linkify_categories("43"); ?>
<?php c2c_linkify_categories("books"); ?>
<?php c2c_linkify_categories("43 92 102"); ?>
<?php c2c_linkify_categories("book movies programming-notes"); ?>
<?php c2c_linkify_categories("book 92 programming-notes"); ?>
<?php c2c_linkify_categories("43,92,102"); ?>
<?php c2c_linkify_categories("book,movies,programming-notes"); ?>
<?php c2c_linkify_categories("book,92,programming-notes"); ?>
<?php c2c_linkify_categories("43, 92, 102"); ?>
<?php c2c_linkify_categories("book, movies, programming-notes"); ?>
<?php c2c_linkify_categories("book, 92, programming-notes"); ?>
<?php c2c_linkify_categories(array(43,92,102)); ?>
<?php c2c_linkify_categories(array("43","92","102")); ?>
<?php c2c_linkify_categories(array("book","movies","programming-notes")); ?>
<?php c2c_linkify_categories(array("book",92,"programming-notes")); ?>
  • <?php c2c_linkify_categories("43 92"); ?>

Outputs something like:

<a href="">Books</a>, <a href="">Movies</a>

  • <ul><?php c2c_linkify_categories("43, 92", "<li>", "</li>", "</li><li>"); ?></ul>

Outputs something like:

<ul><li><a href="">Books</a></li><li><a href="">Movies</a></li></ul>
  • <?php c2c_linkify_categories(""); // Assume you passed an empty string as the first value ?>

Displays nothing.

  • <?php c2c_linkify_categories("", "", "", "", "", "No related categories."); // Assume you passed an empty string as the first value ?>


No related categories.


The plugin exposes one action for hooking.

c2c_linkify_categories (action)

The ‘c2c_linkify_categories’ hook allows you to use an alternative approach to safely invoke c2c_linkify_categories() in such a way that if the plugin were to be deactivated or deleted, then your calls to the function won’t cause errors in your site.


  • same as for c2c_linkify_categories()


Instead of:

<?php c2c_linkify_categories( "43, 92", 'Categories: ' ); ?>


<?php do_action( 'c2c_linkify_categories', "43, 92", 'Categories: ' ); ?>

Frequently Asked Questions

Q. What happens if I tell it to list something that I have mistyped, haven’t created yet, or have deleted?
A. If a given ID/slug doesn’t match up with an existing category then that item is ignored without error.

Q. How do I get items to appear as a list (using HTML tags)?
A. Whether you use the template tag or the widget, specify the following information for the appropriate fields/arguments:

Before text: <ul><li> (or <ol><li>)
After text: </li></ul> (or </li></ol>)
Between categories: </li><li>

Q. Does this plugin include unit tests?
A. Yes.

Release Log

2.1.3 (2015-08-12)

  • Update: Discontinue use of PHP4-style constructor invocation of WP_Widget to prevent PHP notices in PHP7
  • Update: Minor widget header reformatting
  • Update: Minor widget file code tweaks (spacing, bracing)
  • Update: Minor inline document tweaks (spacing)
  • Note compatibility through WP 4.3+

2.1.2 (2015-02-11)

  • Note compatibility through WP 4.1+
  • Update copyright date (2015)

2.1.1 (2014-08-26)

  • Minor plugin header reformatting
  • Change documentation links to to be https
  • Note compatibility through WP 4.0+
  • Add plugin icon

2.1 (2013-12-20)

  • Validate category is either int or string before handling
  • Add unit tests
  • Minor code tweaks (spacing, bracing)
  • Minor documentation tweaks
  • Note compatibility through WP 3.8+
  • Update copyright date (2014)
  • Change donate link
  • Add banner


  • Add check to prevent execution of code if file is directly accessed
  • Note compatibility through WP 3.5+
  • Update copyright date (2013)
  • Create repo’s assets directory
  • Move screenshot into repo’s assets directory


  • Re-license as GPLv2 or later (from X11)
  • Add ‘License’ and ‘License URI’ header tags to readme.txt and plugin file
  • Remove ending PHP close tag
  • Note compatibility through WP 3.4+


  • Note compatibility through WP 3.3+
  • Add link to plugin directory page to readme.txt
  • Update copyright date (2012)


  • Note compatibility through WP 3.2+
  • Minor code formatting changes (spacing)
  • Fix plugin homepage and author links in description in readme.txt


  • Add Linkify Categories widget
  • Rename linkify_categories() to c2c_linkify_categories() (but maintain a deprecated version for backwards compatibility)
  • Rename ‘linkify_categories’ action to ‘c2c_linkify_categories’ (but maintain support for backwards compatibility)
  • Add Template Tag, Screenshots, and Frequently Asked Questions sections to readme.txt
  • Add screenshot of widget admin
  • Note compatibility through WP 3.1+
  • Update copyright date (2011)


  • Add filter ‘linkify_categories’ to respond to the function of the same name so that users can use the do_action() notation for invoking template tags
  • Wrap function in if(!function_exists()) check
  • Reverse order of implode() arguments
  • Fix to prevent PHP notice
  • Remove docs from top of plugin file (all that and more are in readme.txt)
  • Note compatibility with WP 3.0+
  • Minor tweaks to code formatting (spacing)
  • Add Filters and Upgrade Notice sections to readme.txt
  • Remove trailing whitespace


  • Add PHPDoc documentation
  • Add title attribute to link for each category
  • Minor formatting tweaks
  • Note compatibility with WP 2.9+
  • Drop compatibility with WP older than 2.8
  • Update copyright date
  • Update readme.txt (including adding Changelog)


  • Initial release

Copyright & Disclaimer

Copyright © 2009-2015 by Scott Reilly (aka coffee2code)

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

Discussion / Support

Have any questions, comments, or suggestions? Please provide them via the plugin’s support forum. I’ll do my best to reply in a timely fashion and help as best I can.

Unfortunately, I cannot provide guaranteed support, nor do I provide support via any other means.

Was this plugin useful useful to you? Consider giving it a rating. If you’re inclined to give it a poor rating, please first post to the support forum to give me a chance to address or explain the situation.