Including Files Into PHP Web Pages

The ability to include external files into PHP web pages is a useful skill. I'll show you how.

Web page headers, menus, footers, ads, all these are candidates for inclusion from an external file. Anything to be published in more than one web page is a likely candidate.

When an included file is edited, the change is effective in all web pages that include the file. This makes updating easier and faster than editing every web page individually.

The external file may contain any HTML marked-up text, including JavaScript. In other words, if it is OK in a regular web page, it is OK in an external file for inclusion with PHP.

To include a file, first determine what it's URI is. The URI is the URL minus the http:// and domain name.

If the URL is "http://example.com/pieces/file.php" then the URI is "/pieces/file.php"

Here is the way to include an external file:

<?php
readfile($_SERVER['DOCUMENT_ROOT']."[URI]");
?>

Replace [URI] with the URI of the file to include. Using the previous URI example, the file would be included this way (with quotation marks as in the example):

<?php
readfile($_SERVER['DOCUMENT_ROOT']."/pieces/file.php");
?>

Put the PHP to include the external file into the web page source code where the external file is to be published.

When External File Contains PHP Code

If the external file itself contains PHP code, use function include() instead of function readfile().

Here is the way to include an external file that itself contains PHP code:

<?php
include($_SERVER['DOCUMENT_ROOT']."[URI]");
?>

As before, replace [URI] with the URI of the file to include. Using the previous URI example, the file would be included this way:

<?php
include($_SERVER['DOCUMENT_ROOT']."/pieces/file.php");
?>

That is know how to include external files into PHP web pages. It is a useful skill to have.

Will Bontrager