Including files in PHP is a powerful way to reuse code, separate concerns, and improve code organization. There are a few ways to include files:
The include statement includes and evaluates a specified file during the execution of the script. If the file is not found or cannot be included for any reason, it will produce a warning but continue the script execution.
include 'header.php'; // Include header.php file
include 'footer.php'; // Include footer.php file
The require statement is similar to include, but it produces a fatal error if the specified file cannot be included. It halts the script execution if the file is not found.
require 'config.php'; // Require config.php file
require 'functions.php'; // Require functions.php file
These statements work similarly to include and require, respectively, but they only include the file once. If the file has already been included, it won't be included again.
include_once 'header.php'; // Include header.php file only once
require_once 'footer.php'; // Require footer.php file only once
Let's say we have two files: header.php and footer.php.
header.php:
<!DOCTYPE html>
<html>
<head>
<title>My Website</title>
</head>
<body>
<header>
<h1>Welcome to my website</h1>
<nav>
<ul>
<li><a href="#">Home</a></li>
<li><a href="#">About</a></li>
<li><a href="#">Contact</a></li>
</ul>
</nav>
</header>
footer.php:
<footer>
<p>© <?php echo date("Y"); ?> My Website</p>
</footer>
</body>
</html>