PHP relative path problem

When requiring and including a file in PHP, relative paths are mostly used, which is a headache. │

│ │

│ └2.php

└index.php

Problem: In 1.php, include ("../B/2.php") is used to introduce the 2.php file in the B directory;

in In index.php, include ("A/1.php") is used to introduce the 1.php file in the A directory;

Of course there will be problems when running it, and the ../B/2.php file cannot be found.

Remember one principle, all include statements are eventually converted into include paths based on the include file path. It is recommended to use a basic path as a reference for all paths, such as __FILE__ or $_SERVER['DOCUMENT_ROOT']

__

FILE__: (suitable for various situations)

Configure the site root directory in the config file

define( "WEB_ROOT ", dirname(__FILE__) );

The config file is placed in the root directory of the website,

Other files include configuration files ,

When including other files, just locate them according to WEB_ROOT.

require_once( WEB_ROOT . "/a.php " );

$_SERVER['DOCUMENT_ROOT'], suitable for non-virtual host (Alias) situation Php code

<?php  
if (!defined("WETSITE_BASE_DIR"))  
define("WETSITE_BASE_DIR", $_SERVER[&#39;DOCUMENT_ROOT&#39;].&#39;/Clare/&#39;);      
require_once(WETSITE_BASE_DIR.&#39;includes/global.inc.php&#39;);  
?>