How can I define the constant for absolute path only once in PHP?

Question

I have the following files:

• admin/config.php
• header.php
• index.php
• contact/index.php

Both index.php and contact/index.php call header.php. And header.php calls admin/config.php which sets the website root path WEBSITE_HTTP_ROOT . I need WEBSITE_HTTP_ROOT to be able to provide the link to the main page.

Here is header.php:

<?php
require_once('./admin/config.php');
?>
  <div id="menu">
    <a href="http://<?php echo WEBSITE_HTTP_ROOT; ?>" id="logo">website</a>
  </div>

The line require_once('./admin/config.php'); works when called by index.php, but does not work when called by contact/index.php, because the working folder is different.

How can I define the constant for absolute path only once? and be able to call it from anywhere? or how to best avoid the above problem?

Answer 1

One solution is to always include files using the relative path from the current php file location obtainable using dirname(__FILE__) .

For example, in header.php , you would include config.php with:

require_once(realpath(dirname(__FILE__)) . './admin/config.php');

Then in index.php :

require_once(realpath(dirname(__FILE__)) . './header.php');

and in contact/index.php :

require_once(realpath(dirname(__FILE__)) . '../header.php');

Answer 2

You could define a base url parameter:

define ( 'BASEURL', 'http://www.domain.com' );

And then use: <a href="<?= BASEURL ?>/header.php"> Or for front page, just

<a href="<?= BASEURL ?>">

Otherwise, just reference it as:

<a href ="/header.php">

or for frontpage:

 <a href ="/">

Answer 3

In fact, I found a work-around (for now) since I did the include of config.php already in the main index.php, I did not need to re-include the config.php in the header.php.

So following code works fine:

<?php
?>
  <div id="menu">
    <a href="http://<?php echo WEBSITE_HTTP_ROOT; ?>" id="logo">website</a>
  </div>

this does not really answer the question... but it fixes my problem. Might be useful for someone else.