[WordPress] Generates XML Sitemap

index.php

<?

/*
Plugin Name: Sitemap Generator
Description: Generates a XML sitemap For Google Webmaster tools
*/

// On publish of post, update sitemap
add_action("publish_post", "sitemap_gen");
// Update of page
add_action("publish_page", "sitemap_gen");
// If revised post/page
add_action("save_post", "sitemap_gen");
// On activation, create sitemap
register_activation_hook( __FILE__, 'sitemap_gen');

// Query DB for posts/pages, you can edit this to show custom posts type where noted
function sitemap_gen() {
  $postsque = get_posts(array(
    'numberposts' => -1,
    'orderby' => 'modified',
    'post_type'  => array('post','page'), // array('post','page', 'Custom-Post-Type'),
    'order'    => 'DESC'
  ));

// Create XML
$sitemap = '<?xml version="1.0" encoding="UTF-8"?>';
$sitemap .= "\n".'<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">'."\n";

    foreach($postsque as $post) {
        setup_postdata($post);
        $postdate = explode(" ", $post->post_modified);
        $sitemap .= "\t".'<url>'."\n".
            "\t\t".'<loc>'. get_permalink($post->ID) .'</loc>'.
            "\n\t\t".'<lastmod>'. $postdate[0] .'</lastmod>'.
            "\n\t\t".'<changefreq>monthly</changefreq>'.
            "\n\t".'</url>'."\n";
    }
$sitemap .= '</urlset>';
$fp = fopen(ABSPATH . "sitemap.xml", 'w');
fwrite($fp, $sitemap);
fclose($fp);
    }

?>