<?php

  require('reusable.php');

  echo "相对路径加载<br/>";

  /*

    ./  表示当前文件所在的目录

    ../ 表示当前文件所在目录的上一级目录

  */

  include ("./includedfile.php");

  echo "<br/>";

  echo "绝对路径加载,__DIR__，方法一<br/>";

  include(__DIR__."/includedfile.php");

  echo "<br/>";

  echo "绝对路径加载，\$_server['DOCUMENT_ROOT'],方法二<br />";

  echo "根目录:".$_SERVER['DOCUMENT_ROOT']."<br />";

  include($_SERVER['DOCUMENT_ROOT']."/includedfile.php");

 ?>