PHP Functions

Including files is very useful when you want to include the same PHP, HTML, or text on multiple pages of a website.

Inbuilt Functions

include():-The include() function is used to include a file to another file.

include_onnce:-If the code form a file has been already included then it will not be include again,if we use include_once().
include_once() include the file only once at a time.

Requie():-is same as Include()

Requie_once():-is same as include_once()

isset()

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.

include Statement

include will only produce a warning (E_WARNING) and the script will continue

If you want the execution to go on and show users the output, even if the include file is missing, use the include statement.

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';

Assume we have a standard footer file called "footer.php", that looks like this:

<?php
echo "<p>Copyright © 1999-" . date("Y") . " php.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>

Run Example>>

require Statement

The require statement is also used to include a file into the PHP code.

require will produce a fatal error (E_COMPILE_ERROR) and stop the script

Syntax

require 'filename';

If we do the 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>

Run Example>>