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);
}
?>