Is there a guide to path referencing in PHP?

Question

I know how to include files that are in folders further down the heirachy but I have trouble finding my way back up. I decided to go with the set_include_path to default all further includes relative to a path 2 levels up but don't have the slightest clue how to write it out.

Is there a guide somewhere that details path referencing for PHP?

Answer 1

it's probably easier to just use an absolute path to reference:

set_include_path('/path/to/files');

this way you have a reference point for all your future includes. includes are handled relative to the point they were called, which can cause a bit of confusion in certain scenarios.

as an example, given a sample folder structure (/home/files):

index.php
test/
  test.php
test2/
  test2.php

// /home/files/index.php
include('test/test.php');

// /home/files/test/test.php
include('../test2/test2.php');

if you call index.php, it will try to include the following files:

/home/files/test/test.php // expected
/home/test2/test2.php // maybe not expected

which may not be what you expect. calling test.php will call /home/files/test2/test.php as expected.

the conclusion being, the includes will be relative to the original calling point. to clarify, this affects set_include_path() if it is relative as well. consider the following (using the same directory structure):

<?php
// location: /home/files/index.php
   set_include_path('../'); // our include path is now /home/

   include('files/test/test.php'); // try to include /home/files/test/test.php
   include('test2/test2.php'); // try to include /home/test2/test2.php
   include('../test3.php'); // try to include /test3.php
?>

Answer 2

I tend to use dirname to get the current path and then use this as a base to calculate all future path names.

For example,

$base = dirname( __FILE__ ); # Path to directory containing this file
include( "{$base}/includes/Common.php" ); # Kick off some magic