function代码
//pc:相当于菜单id可以随意命名register_nav_menus( array( 'pc' => '电脑') );
前台调用
//pc:function中注册菜单的id<?php wp_nav_menu( array( 'theme_location' => 'pc','container_id' => 'weihuan-header-num','container_class' => 'weihuan-header-num', 'fallback_cb' => 'default_menu' ) ); ?>