get_permalink( $id, $leavename );

<a href="<?php echo get_permalink( 268 ); ?>">獲取指定 ID 的文章或頁面鏈接</a>

<?php echo get_permalink(); ?>

<a href="<?php echo esc_url( get_permalink( get_page_by_title( '留言板' ) ) ); ?>">留言板</a>

wp_title( $sep, $display, $seplocation );

/**
 * 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 $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 post
  if ( is_single() || ( is_home() && !is_front_page() ) || ( is_page() && !is_front_page() ) ) {
    $title = single_post_title( '', false );
  }
 
  // If there's a post type archive
  if ( is_post_type_archive() ) {
    $post_type = get_query_var( 'post_type' );
    if ( is_array( $post_type ) )
      $post_type = reset( $post_type );
    $post_type_object = get_post_type_object( $post_type );
    if ( ! $post_type_object->has_archive )
      $title = post_type_archive_title( '', false );
  }
 
  // If there's a category or tag
  if ( is_category() || is_tag() ) {
    $title = single_term_title( '', false );
  }
 
  // If there's a taxonomy
  if ( is_tax() ) {
    $term = get_queried_object();
    if ( $term ) {
      $tax = get_taxonomy( $term->taxonomy );
      $title = single_term_title( $tax->labels->name . $t_sep, false );
    }
  }
 
  // If there's an author
  if ( is_author() && ! is_post_type_archive() ) {
    $author = get_queried_object();
    if ( $author )
      $title = $author->display_name;
  }
 
  // Post type archives with has_archive should override terms.
  if ( is_post_type_archive() && $post_type_object->has_archive )
    $title = post_type_archive_title( '', false );
 
  // If there's a month
  if ( 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 year
  if ( 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 search
  if ( 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 page
  if ( is_404() ) {
    $title = __('Page not found');
  }
 
  $prefix = '';
  if ( !empty($title) )
    $prefix = " $sep ";
 
  /**
   * Filter the parts of the page title.
   *
   * @since 4.0.0
   *
   * @param array $title_array Parts of the page title.
   */
  $title_array = apply_filters( 'wp_title_parts', explode( $t_sep, $title ) );
 
   // Determines position of the separator and direction of the breadcrumb
  if ( 'right' == $seplocation ) { // sep on right, so reverse the order
    $title_array = array_reverse( $title_array );
    $title = implode( " $sep ", $title_array ) . $prefix;
  } else {
    $title = $prefix . implode( " $sep ", $title_array );
  }
 
  /**
   * Filter the text of the page title.
   *
   * @since 2.0.0
   *
   * @param string $title    Page title.
   * @param string $sep     Title separator.
   * @param string $seplocation Location of the separator (left or right).
   */
  $title = apply_filters( 'wp_title', $title, $sep, $seplocation );
 
  // Send it out
  if ( $display )
    echo $title;
  else
    return $title;
 
}

<title><?php wp_title( '|', true, 'right' ); ?></title>