详解WordPress开发中wp_title()函数的用法

wp_title 函数在 WordPress 中是用来显示文章、页面、分类等等等等标题的一个函数，但在首页索引，该函数将不显示任何的东西。该函数在 WordPress 官方主题中一直被使用，但目前很多定制的主题中这个函数总是为忽视。

函数意义详解
wp_title 函数用来显示页面的标题，如在文章页面，则显示文章标题；在分类页面，则显示分类名称，但在首页索引，该函数将不显示任何的东西。
有点像 WordPress 中的 get_the_title 和 single_cat_title()这两个函数的自适应用法（自动判断是页面、文章还是分类、归档、标签）。

函数声明
有点长，希望您能耐心看一遍，哪怕只有那么一遍。

/** * Display or retrieve page title for all areas of blog. * * By default, the page title will display the separator before the page title, * so that the blog title will be before the page title. This is not good for * title display, since the blog title shows up on most tabs and not what is * important, which is the page that the user is looking at. * * There are also SEO benefits to having the blog title after or to the 'right' * or the page title. However, it is mostly common sense to have the blog title * to the right with most browsers supporting tabs. You can achieve this by * using the seplocation parameter and setting the value to 'right'. This change * was introduced around 2.5.0, in case backwards compatibility of themes is * important. * * @since 1.0.0 * * @param string $sep Optional, default is '»'. How to separate the various items within the page title. * @param bool $display Optional, default is true. Whether to display or retrieve title. * @param string $seplocation Optional. Direction to display title, 'right'. * @return string|null String on retrieve, null when displaying. */function wp_title($sep = '»', $display = true, $seplocation = '') {global $wpdb, $wp_locale; $m = get_query_var('m');$year = get_query_var('year');$monthnum = get_query_var('monthnum');$day = get_query_var('day');$search = get_query_var('s');$title = ''; $t_sep = '%WP_TITILE_SEP%'; // Temporary separator, for accurate flipping, if necessary // If there is a postif ( is_single() || ( is_home() && !is_front_page() ) || ( is_page() && !is_front_page() ) ) { $title = single_post_title( '', false );} // If there's a category or tagif ( is_category() || is_tag() ) { $title = single_term_title( '', false );} // If there's a taxonomyif ( is_tax() ) { $term = get_queried_object(); $tax = get_taxonomy( $term->taxonomy ); $title = single_term_title( $tax->labels->name . $t_sep, false );} // If there's an authorif ( is_author() ) { $author = get_queried_object(); $title = $author->display_name;} // If there's a post type archiveif ( is_post_type_archive() ) $title = post_type_archive_title( '', false ); // If there's a monthif ( is_archive() && !empty($m) ) { $my_year = substr($m, 0, 4); $my_month = $wp_locale->get_month(substr($m, 4, 2)); $my_day = intval(substr($m, 6, 2)); $title = $my_year . ( $my_month ? $t_sep . $my_month : '' ) . ( $my_day ? $t_sep . $my_day : '' );} // If there's a yearif ( is_archive() && !empty($year) ) { $title = $year; if ( !empty($monthnum) ) $title .= $t_sep . $wp_locale->get_month($monthnum); if ( !empty($day) ) $title .= $t_sep . zeroise($day, 2);} // If it's a searchif ( is_search() ) { /* translators: 1: separator, 2: search phrase */$title = sprintf(__('Search Results %1$s %2$s'), $t_sep, strip_tags($search));} // If it's a 404 pageif ( is_404() ) { $title = __('Page not found');} $prefix = '';if ( !empty($title) ) $prefix = " $sep "; // Determines position of the separator and direction of the breadcrumbif ( 'right' == $seplocation ) { // sep on right, so reverse the order$title_array = explode( $t_sep, $title );$title_array = array_reverse( $title_array );$title = implode( " $sep ", $title_array ) . $prefix;} else { $title_array = explode( $t_sep, $title ); $title = $prefix . implode( " $sep ", $title_array );} $title = apply_filters('wp_title', $title, $sep, $seplocation); // Send it out if ( $display ) echo $title; else return $title; }