php-include-require
include will have the server insert the contents of a file in your current file
before parsing it...
If an error occurs, the include() function generates a warning, but the script will continue. "require()" does the same thing but will halt on errors.
EXAMPLES:
<?php include("head.txt"); ?>
<?php include("footer.php"); ?>
so
main.php
<?php
include some-function.txt
some_function();
?>
some-function.txt
<?php
?>
To ensure that a piece of code is only added once...
include_once or the require_once
<?php
$servername = $_SERVER['SERVER_NAME'];
$filename = "http://" . $servername . "/head.txt";
include($filename);
?>
<?php
$servername = $_SERVER['SERVER_NAME'];
$filename = "http://" . $servername . "/foot.txt";
include($filename);
?>
-------------------------------------
PHP 5 improves default security settings so that "include" does not allow random url's
A better way then is:
$path_to_be = $_SERVER["DOCUMENT_ROOT"];
echo $path_to_be . "\n<br />";
include( $_SERVER["DOCUMENT_ROOT"] . "/includes/footer.htm");