WordPress中用于获取搜索表单的PHP函数使用解析

<?php
  get_search_form($echo = true) 
?>

<?php
  get_search_form(); 
?>

<?php
 /
  Display search form.
 
  Will first attempt to locate the searchform.php file in either the child or
  the parent, then load it. If it doesn't exist, then the default search form
  will be displayed. The default search form is HTML, which will be displayed.
  There is a filter applied to the search form HTML in order to edit or replace
  it. The filter is 'get_search_form'.
 
  This function is primarily used by themes which want to hardcode the search
  form into the sidebar and also by the search widget in WordPress.
 
  There is also an action that is called whenever the function is run called,
  'get_search_form'. This can be useful for outputting JavaScript that the
  search relies on or various formatting that applies to the beginning of the
  search. To give a few examples of what it can be used for.
 
  @since 2.7.0
  @param boolean $echo Default to echo and not return the form.
 /
function get_search_form($echo = true) {
 do_action( 'get_search_form' );
 
 $search_form_template = locate_template('searchform.php');
 if ( '' != $search_form_template ) {
 require($search_form_template);
 return;
 }
 
 $form = '<form role="search" method="get" id="searchform" action="' . esc_url( home_url( '/' ) ) . '" >
 <div><label class="screen-reader-text" for="s">' . __('Search for:') . '</label>
 <input type="text" value="' . get_search_query() . '" name="s" id="s" />
 <input type="submit" id="searchsubmit" value="'. esc_attr__('Search') .'" />
 </div>
 </form>';
 
 if ( $echo )
 echo apply_filters('get_search_form', $form);
 else
 return apply_filters('get_search_form', $form);
}
?>