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PHP Tutorial >> The Include Function The Include Function
Without understanding much about the details of PHP, you can
save yourself a great deal of time with the use of the PHP include
function. The include function takes a file name and simply
inserts that files contents into the file that calls the include function.
Why is this a cool thing? Well, first of all, this means that you can type
up a common header or menu file that you want all your web pages to include.
When you add a new page to your site, instead of having to update the links
on tens of separate web pages, you can simply change the Menu file.
An Include Example
Say we wanted to create a common menu file that all our pages
will use. For easy reference, files that are to be included usually
are named with a ".inc" extension. Since we want to create a common menu,
let us save it as "menu.inc".
menu.inc Code:
<html>
<body>
<a href="index.php">Home</a> -
<a href="about.php">About Us</a> -
<a href="links.php">Links</a> -
<a href="contact.php">Contact Us</a> <br />
Save the above file as "menu.inc". Now create a new file, "index.php" in the same directory as
"menu.inc". Here we will take advantage of the include function to add our common menu.
index.php Code:
<?php include("menu.inc"); ?>
<p>This is my home page that uses a common menu to save me time when I add
new pages to my website!</p>
</body>
</html>
And we would do the same thing for "about.php", "links.php", and "contact.php". Just think
how terrible it would be if you had 15 or more pages with a common menu and you decided to add
another web page to that site. Avoid such troublesome occasions with a simple include file.
What do Visitor's See?
If we were to use the include function to include a common menu on each of our web pages, what
would the visitor see if they viewed the source, of "index.php". Well because the include function
is pretty much the same as a copy and paste of the text, the visitors would see:
View Source of index.php to a Visitor:
<html>
<body>
<a href="index.php">Home</a> -
<a href="about.php">About Us</a> -
<a href="links.php">Links</a> -
<a href="contact.php">Contact Us</a> <br />
<p>This is my home page that uses a common menu to save me time when I add
new pages to my website!</p>
</body>
</html>
The visitor would actually see all the HTML code as one long line of HTML code, because
we have not inserted any new line characters. We did some formatting above to make it easier to read.
We will be discussing new line characters later.
Include Recap
The include command simply takes all the text that exists in the specified file and copies
it into the file that uses the include function. Include is quite useful when you want
to include the same PHP, HTML, or text segment on multiple pages of a website. The include
function is used widely by advanced web developers.
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