PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

136 Chapter 5 Reusing Code and Writing Functions
A file is needed to use a require() statement. In the preceding example, you used the
file named reusable.php.When you run the script, the require() statement
require( ‘reusable.php’ );
is replaced by the contents of the requested file, and the script is then executed.This
means that when you load main.php, it runs as though the script were written as
follows:
When using require(), you need to note the different ways filename extensions and
PHP tags are handled.
PHP does not look at the filename extension on the required file.This means that
you can name your file whatever you choose as long as you do not plan to call it directly.When
you use require() to load the file, it effectively becomes part of a PHP file
and is executed as such.
Normally, PHP statements would not be processed if they were in a file called, for
example, page.html. PHP is usually called upon to parse only files with defined extensions
such as .php. (This may be changed in your web server configuration file.)
However, if you load page.html via a require() statement, any PHP inside it will be
processed.Therefore, you can use any extension you prefer for include files, but sticking
to a sensible convention such as .inc or .php would be a good idea.
One issue to be aware of is that if files ending in .inc or some other nonstandard
extension are stored in the web document tree and users directly load them in the
browser, they will be able to see the code in plain text, including any passwords. It is
therefore important to either store included files outside the document tree or use the
standard extensions.
Note
In the example, the reusable file (reusable.php) was written as follows:
The PHP code was placed within the file in PHP tags.You need to follow this convention
if you want PHP code within a required file treated as PHP code. If you do not
open a PHP tag, your code will just be treated as text or HTML and will not be
executed.