Mac's WordPress Tips

The code below is for a template for the WP 2.9 default theme that lists categories by the first letter of the category name.

An updated version of this code, with the capability to list terms of any taxonomy is shown in this post.

<?php
/**
 * @package WordPress
 * @subpackage Default_Theme
 */
/*
Template Name: listcatsbyletter
*/
?>
<?php /*
 Author: Mac McDonald
 Contact at BluegrassMiataClub.com using About->Contact Us form.

 This program creates a list of categories as links to the archive for
 each category.

 Set $hide_uncategorized = false; to show the uncategorized category.
     $hide_description = true; to hide the description of each category.
     $limit = the number of categories (not including Letters) per page.
     $range = number of page links in the nav bar. (5 is a good number).
*/?>

<?php get_header(); ?>

<?php
$hide_uncategorized = true;
$hide_description = false;
$limit = 25;  // Show this many entries per page
$range = 5;  // Show this many nav bar page links (other than first & last).
$args = array('orderby' => 'name', 'order' => 'ASC');
if ($hide_uncategorized) $args['exclude'] = '1';
$categories = get_categories($args);
if ($categories) :
   // For some unknown reason, $categories has no [0] entry at times, so renumber.
   $categories = array_merge($categories,array());
   if (isset($_GET['page'])) {
      $page = $_GET['page'];
   } else {
      $page = 1;
   }
   $start = ($page - 1) * $limit;
   $currletter = '';
   echo '<ul class="category_list">';
   for ($i=$start;$i<($start + $limit);++$i) {
      if ($i < sizeof($categories)) {
         $cat =  $categories[$i];
         $catletter = strtoupper(substr($cat->name,0,1));
         if ($currletter != $catletter) {
            if ($currletter != '') echo '</ul>';
            $currletter = $catletter;
            echo "<h2> - $catletter - </h2>";
            echo '<ul>';
         }
         echo '<li class="category_entry">Category: <a href="' . get_category_link( $cat->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $cat->name ) . '" ' . '>' . $cat->name.'</a> </p> ';
         if (!$hide_description) echo '<p>Description: '. $cat->description . '</p>';
         echo '</li>';
      }
   }
   echo '<br /><br />';
   echo _cat_paginate(sizeof($categories),$limit,$range);
   echo '</ul>';
else:
   echo '<h2></h2>';
   echo 'There are no Categories to list';
endif;?>

<?php get_footer(); ?>

<?php function _cat_paginate($numrows,$limit=10,$range=7) {

   $pagelinks = "<div class=\"pagelinks\">";
   $currpage = $_SERVER['PHP_SELF'] . "?" . $_SERVER['QUERY_STRING'];
   if ($numrows > $limit) {
      if(isset($_GET['page'])){
         $page = $_GET['page'];
      } else {
         $page = 1;
      }
      $currpage = $_SERVER['PHP_SELF'] . "?" . $_SERVER['QUERY_STRING'];
      $currpage = str_replace("&page=".$page,"",$currpage);
      if($page == 1){
         $pagelinks .= "<span class=\"pageprevdead\">&laquo PREV </span>";
      }else{
         $pageprev = $page - 1;
         $pagelinks .= "<a class=\"pageprevlink\" href=\"" . $currpage .
               "&page=" . $pageprev . "\">&laquo PREV </a>";
      }
      $numofpages = ceil($numrows / $limit);
      if ($range == "" or $range == 0) $range = 7;
      $lrange = max(1,$page-(($range-1)/2));
      $rrange = min($numofpages,$page+(($range-1)/2));
      if (($rrange - $lrange) < ($range - 1)) {
         if ($lrange == 1) {
            $rrange = min($lrange + ($range-1), $numofpages);
         } else {
            $lrange = max($rrange - ($range-1), 0);
         }
      }
      if ($lrange > 1) {
         $pagelinks .= "<a class=\"pagenumlink\" " .
            "href=\"" . $currpage . "&page=" . 1 .
            "\"> [1] </a>";
         if ($lrange > 2) $pagelinks .= "&nbsp;...&nbsp;";
      } else {
         $pagelinks .= "&nbsp;&nbsp;";
      }
      for($i = 1; $i <= $numofpages; $i++){
         if ($i == $page) {
            $pagelinks .= "<span class=\"pagenumon\"> [$i] </span>";
         } else {
            if ($lrange <= $i and $i <= $rrange) {
               $pagelinks .= "<a class=\"pagenumlink\" " .
                        "href=\"" . $currpage . "&page=" . $i .
                        "\"> [" . $i . "] </a>";
            }
         }
      }
      if ($rrange < $numofpages) {
         if ($rrange < $numofpages - 1) $pagelinks .= "&nbsp;...&nbsp;";
            $pagelinks .= "<a class=\"pagenumlink\" " .
               "href=\"" . $currpage . "&page=" . $numofpages .
               "\"> [" . $numofpages . "] </a>";
      } else {
         $pagelinks .= "&nbsp;&nbsp;";
      }
      if(($numrows - ($limit * $page)) > 0){
         $pagenext = $page + 1;
         $pagelinks .= "<a class=\"pagenextlink\" href=\"" . $currpage .
                    "&page=" . $pagenext . "\"> NEXT &raquo;</a>";
      } else {
         $pagelinks .= "<span class=\"pagenextdead\"> NEXT &raquo;</span>";
      }

   }
$pagelinks .= "</div>";
return $pagelinks;
}
?>