Since I change the tree, absolute and relative path don't work

Question

I tried to use the absolute path to include my files :

I have 4 files (I have other file on my localhost but oddly the inclusion works well) :

header.php (C:\wamp\www\MySite\layout\header.php)

<?php session_start (); 
require_once '/pdo.php';
....

pdo.php (C:\wamp\www\MySite\pdo.php)

<?php
require_once '/class/User.php';
require_once '/class/Order.php';
....

forms/login.php (C:\wamp\www\MySite\forms\login.php)

<?php
session_start (); 
include '/pdo.php';
....

login.php (C:\wamp\www\MySite\login.php)

<?php
  $title = 'Connexion'; 
  include ("/layout/header.php");
...

So it's look like :

Root
    - forms
        - login.php
    -layout
        - header.php
    - pdo.php
    - login.php

And I have this errors :

( ! ) Warning: include(/pdo.php): failed to open stream: No such file or directory in C:\wamp\www\MySite\forms\login.php on line 3 Call Stack

( ! ) Warning: include(): Failed opening '/pdo.php' for inclusion (include_path='.;C:\php\pear') in C:\wamp\www\MySite\forms\login.php on line 3

( ! ) Fatal error: Class 'User' not found in C:\wamp\www\MySite\forms\login.php on line 12

But I have this problem on a lot of files since I wanted to change the arboresence (tree) of files and folder ..

How I can solve this problem ? and how I can do to avoid this problem in the future ?

Thank you

Answer 1

I tried to use the absolute path to include my files :

header.php (C:\wamp\www\MySite\layout\header.php)

<?php session_start (); 
require_once '/pdo.php';

The PHP code is executed on the server. An absolute path in this context means a file-system absolute path, not a web host path. Since you are on Windows, /pdo.php in fact means C:/pdo.php and not C:\wamp\www\MySite\pdo.php as it seems you think.

The best way to work with paths in PHP, regarding include and require is to use the __FILE__ and __DIR__ magic constants and the dirname() PHP function to build the (file-system) absolute paths of files starting from their relative locations.

Your code becomes:

header.php (C:\wamp\www\MySite\layout\header.php):

<?php
session_start (); 
// 'pdo.php' is one level up
require_once dirname(__DIR__).'/pdo.php';
....

pdo.php (C:\wamp\www\MySite\pdo.php)

<?php
// User.php is inside the 'class' subdirectory
require_once __DIR__.'/class/User.php';
require_once __DIR__.'/class/Order.php';
....

dir1/dir2/dir3/file.php (C:\wamp\www\MySite\dir1\dir2\dir3\file.php)

<?php
// 'header.php' is in the 'layout' subdirectory of the grand-grand parent directory
include dirname(dirname(dirname(__DIR__))).'/layout/header.php';

Remark

The solution presented here makes the code independent of its actual location in the file system. You can move the entire project (everything in C:\wamp\www\MySite) in a different directory or on a different computer and it will work without changes. Even more, if you use forward slashes (/) as directory names separators it works on Windows, macOS or any Linux flavor.