PHP
5 Include Files
The include
(or require) statement takes all the text/code/markup that exists in the
specified file and copies it into the file that uses the include statement.
Including
files is very useful when you want to include the same PHP, HTML, or text on
multiple pages of a website.
PHP include
and require Statements
It is
possible to insert the content of one PHP file into another PHP file (before
the server executes it), with the include or require statement.
The include
and require statements are identical, except upon failure:
require will
produce a fatal error (E_COMPILE_ERROR) and stop the script
include will
only produce a warning (E_WARNING) and the script will continue
So, if you
want the execution to go on and show users the output, even if the include file
is missing, use the include statement. Otherwise, in case of FrameWork, CMS, or
a complex PHP application coding, always use the require statement to include a
key file to the flow of execution. This will help avoid compromising your
application's security and integrity, just in-case one key file is accidentally
missing.
Including
files saves a lot of work. This means that you can create a standard header,
footer, or menu file for all your web pages. Then, when the header needs to be
updated, you can only update the header include file.
Syntax
include
'filename';
or
require
'filename';
PHP include
Examples
Example
1
Assume we
have a standard footer file called "footer.php", that looks like
this:
<?php
echo
"<p>Copyright © 1999-" . date("Y") . "
Omega.com</p>";
?>
To include
the footer file in a page, use the include statement:
Example
<html>
<body>
<h1>Welcome
to my home page!</h1>
<p>Some
text.</p>
<p>Some
more text.</p>
<?php
include 'footer.php';?>
</body>
</html>
Example
2
Assume we
have a standard menu file called "menu.php":
<?php
echo
'<a href="/default.html">Home</a> -
<a
href="/html/default.html">HTML Tutorial</a> -
<a
href="/css/default.html">CSS Tutorial</a> -
<a
href="/js/default.html">JavaScript Tutorial</a> -
<a
href="default.html">PHP Tutorial</a>';
?>
All pages in
the Web site should use this menu file. Here is how it can be done (we are
using a <div> element so that the menu easily can be styled with CSS
later):
Example
<html>
<body>
<div
class="menu">
<?php
include 'menu.php';?>
</div>
<h1>Welcome
to my home page!</h1>
<p>Some
text.</p>
<p>Some
more text.</p>
</body>
</html>
Example
3
Assume we
have a file called "vars.php", with some variables defined:
<?php
$color='red';
$car='BMW';
?>
Then, if we
include the "vars.php" file, the variables can be used in the calling
file:
Example
<html>
<body>
<h1>Welcome
to my home page!</h1>
<?php
include 'vars.php';
echo
"I have a $color $car.";
?>
</body>
</html>
PHP include
vs. require
The require
statement is also used to include a file into the PHP code.
However,
there is one big difference between include and require; when a file is
included with the include statement and PHP cannot find it, the script will
continue to execute:
Example
<html>
<body>
<h1>Welcome
to my home page!</h1>
<?php
include 'noFileExists.php';
echo
"I have a $color $car.";
?>
</body>
</html>
If we do the
same example using the require statement, the echo statement will not be
executed because the script execution dies after the require statement returned
a fatal error:
Example
<html>
<body>
<h1>Welcome
to my home page!</h1>
<?php
require 'noFileExists.php';
echo
"I have a $color $car.";
?>
</body>
</html>
Use require
when the file is required by the application.
Use include
when the file is not required and application should continue when file is not
found.
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