You can include the content of a PHP file into another PHP file
before the server executes it. There are two PHP functions which can be
used to included one PHP file into another PHP file.
- The include() Function
- The require() Function
This is a strong point of PHP which helps in creating functions,
headers, footers, or elements that can be reused on multiple pages. This
will help developers to make it easy to change the layout of complete
website with minimal effort. If there is any change required then
instead of changing thousand of files just change included file.
The include() Function
The include() function takes all the text in a specified file and
copies it into the file that uses the include function. If there is any
problem in loading a file then the include() function generates a warning but the script will continue execution.
Assume you want to create a common menu for your website. Then create a file menu.php with the following content.
<a href="http://www.tutorialspoint.com/index.htm">Home</a> - <a href="http://www.tutorialspoint.com/ebxml">ebXML</a> - <a href="http://www.tutorialspoint.com/ajax">AJAX</a> - <a href="http://www.tutorialspoint.com/perl">PERL</a> <br /> |
Now create as many pages as you like and include this file to create
header. For example now your test.php file can have following content.
<html>
<body>
<?php include("menu.php"); ?>
<p>This is an example to show how to include PHP file!</p>
</body>
</html>
|
This will produce following result
|
This is an example to show how to include PHP file. You can include mean.php file in as many as files you like! |
The require() Function
The require() function takes all the text in a specified file and
copies it into the file that uses the include function. If there is any
problem in loading a file then the require() function generates a fatal error and halt the execution of the script.
So there is no difference in require() and include() except they
handle error conditions. It is recommended to use the require() function
instead of include(), because scripts should not continue executing if
files are missing or misnamed.
You can try using above example with require() function and it will
generate same result. But if you will try following two examples where
file does not exist then you will get different results.
<html>
<body>
<?php include("xxmenu.php"); ?>
<p>This is an example to show how to include wrong PHP file!</p>
</body>
</html>
|
This will produce following result
This is an example to show how to include wrong PHP file! |
Now lets try same example with require() function.
<html>
<body>
<?php require("xxmenu.php"); ?>
<p>This is an example to show how to include wrong PHP file!</p>
</body>
</html>
|
This time file execution halts and nothing is displayed.
NOTE: You may get plain warning messages or fatal error messages or nothing at all. This depends on your PHP Server configuration.
include vs. include_once vs. require vs. require_once - examples
include ('sponsor_links.php');
If the file sponsor_links is present in the current folder, it will be included ( way may want it to appear both - at the top and at the bottom).
include_once ('statistics.php');
If the file statistics.php is present, it means we want statistics for the page. Otherwise, we don't want statistics. Deleting statistics.php will not affect the main program.
require ('navigation.php');
We may want to include the navigational links both both at the top and the bottom at the page. If navigation.php is not present, the main program will stop running and an error message will be displayed.
require_once ('google_adsense_top.php');
Because a page has only one top, only one instance of google_adsense_top.php will be included. If google_adsense_top.php is not present, the main program will stop running and an error message will be displayed.
If you want more details about how each of include/require works, please reply to this post.
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