WordPress − returns the number of posts from a category

gistfile1.inc

<?php

/**
 * Returns the number of posts from a category
 * 
 * 
 * @version   1.0
 * @since     2010-03-23
 * @author    Oncle Tom <http://case.oncle-tom.net>
 * @param     integer $category_id
 * @return    integer|NULL Number of posts, NULL if category does not exists
 */
function get_category_count($category_id)
{
  $category_data = get_category($category_id, ARRAY_A);
  
  return !empty($category_data) && isset($category_data['category_count']) ? (int)$category_data['category_count'] : NULL;
}