How to include config.php efficiently?

Question

I'm always interested in more efficient ways and learning new things. Right now, I am using the code <?php include('config.php'); ?> in each and every file. Depending on where the file is in my the folder structure, I would have <?php include('../config.php'); ?> or even <?php include('../../config.php'); ?>. How can I make it more efficient? Is there a way to just have it my config.php in root and make everything in root require config.php?

Answer 1

there is a way to include a file automatically (auto_prepend_file ini setting), however the biggest improvement you can make is to abandon the usage of multiple php files and use index.php as a single entry point for the whole website.

suppose you write a SO clone ;) with the pages "questions", "tags", "users", etc. On each page you need some generic php stuff (db, session) + common html elements (header, footer). A popular approach is to have a bunch of php files (questions.php, tags.php, users.php) each of them includes the common stuff. For example, users.php will look like this then

include 'db.php';
include 'session.php';
include 'html.header.php';
.....users-specific stuff 
include 'html.footer.php';

This is quite tedious (you have to repeat lots of code) and inflexible (think adding a sidebar to all pages on the site). My suggestion is to make includes "inside out" that is, have a "common stuff" file that includes page-specific code:

 # index.php
 db functions
 session functions
 html header

 $page = isset($_GET['page']) 
   ? preg_replace("/\W+/", "", $_GET['page'])
   : "home";
 include "$page.php";

 html footer

Thus you'll have a single entry point on the website - this is more flexible and better for debugging. The only drawback is that urls are less "nice" (user.php vs index.php?page=user), but this can be easily solved with mod_rewrite

Answer 2

Put the path containing config.php in your php include path and then you can simply do this:

include 'config.php';

or better yet:

require_once 'config.php';

require is preferred over include because it triggers an error instead of a warning when a file cannot be included for some reason (e.g. file not found, permissions error, etc.). The _once suffix is a good addition to make sure the same file isn't needlessly included multiple times.

Also, please note that you don't need the parenthesis around 'config.php' in your include call. include is not a function in php. It's a language construct. The parenthesis just serve as a needless grouping not unlike this example: $myVar = (2 + 2);.