来自不同目录级别的两个文件同时调用同一个文件：
// index.php
include('./include/same_file.php');
// Webpages/page1.php
include('../include/same_file.php');
// include/same_file.php
include('../template/header.php'); // failed to open on index.php
fopen('../files/text1.txt'); // failed to open on index.php
file('./files/AA.html'); // failed to open on /include/same_file.php
我花了几个小时寻找解决方案，找到了dirname(__FILE__)和$_SERVER[DOCUMENT_ROOT]解决方案，但都不起作用，因为它们都没有为像我这样的初学者提供详细的教学
试试这个。。
require_once(__DIR__."/include/same_file.php");
或
include(__DIR__."/include/same_file.php");