Understanding the 'include' Statement in PHP

The 'include' statement holds a significant place in PHP. It is used to include and execute the specified file. This PHP feature primarily allows reusing PHP code across multiple pages, which in turn makes code more streamlined, manageable, and efficient.

Let's understand this with an example. Suppose you have a PHP file called 'header.php'. Now, this file contains your website's header section that includes the navigation menu, logo, and other important elements that remain the same across different pages of the website. Instead of writing this code repeatedly on every page, you can simply create this 'header.php' file once and include it on other pages using the 'include' statement.

Here's how it works:

<?php include 'header.php'; ?>

This line of code includes the entire content and conducts the relevant PHP operations from the 'header.php' file wherever it's placed.

Now, let's attend to an important aspect - what happens if the file specified in the 'include' statement is not found? Well, 'include' produces a warning in such an instance but the script continues to execute the rest of the page.

Alternatively, PHP also has 'require' statement which serves a similar purpose as 'include', but with a notable difference - if the filename provided to the 'require' statement is not found, it causes a fatal error and halting the execution of the script. Depending upon the nature of your project and the importance of the file you want to include, you can decide between using 'include' or 'require'.

Always remember to maintain clean and organized code while using the 'include' statement. Too many included files can make your code complex and challenging to debug, especially when files are included within included files.