PHP Include and Require

 

 

PHP Include and Require

PHP allows us to create various elements and functions, which are used several times in many pages. It takes much time to script these functions in multiple pages. In PHP, the concept of file inclusion is a powerful feature that allows developers to reuse code efficiently across multiple pages. This becomes especially valuable when dealing with common elements or functions that are used repeatedly.

The Need for File Inclusion in PHP:

Code Reusability:

• 1.     When creating web applications or websites, there are often elements or functions that need to be used across multiple pages.
• 2.     Instead of duplicating the code in every page, PHP provides a way to encapsulate this common functionality in separate files.

Efficient Maintenance:

• 1.     Writing modular and organized code is a good practice, making it easier to manage and maintain.
• 2.     By using file inclusion, developers can break down their code into smaller, focused files, promoting a clean and maintainable codebase.

Practical Benefits:

• 1.     Effort Reduction: By using file inclusion, developers save time and effort by avoiding the need to rewrite common code segments across multiple pages.
• 2.     Consistent Elements: Elements like headers, footers, or functions can be centralized in separate files, ensuring consistency and reducing the chance of errors.
• 3.     Improved Readability: Breaking down code into modular files enhances code readability, making it easier for developers to understand and collaborate on projects.

"PHP allows you to include file so that a page content can be reused many times. It is very helpful to include files when you want to apply the same HTML or PHP code to multiple pages of a website."

There are two ways to include file in PHP.

1.     include

2.     require

PHP include

PHP include is used to include a file on the basis of given path. You may use a relative or absolute path of the file.

Syntax

There are two syntaxes available for include:

include 'filename ';  

Or   

include ('filename');  

Functionality:

• 1.     The include statement includes the specified file (filename.php) at the point where it's written in the code.
• 2.     It executes the code in the included file as if it were part of the main file.
• 3.     If the file is not found or there is an error during inclusion, a warning is issued, but the script continues execution.

Use Cases:

• 1.     Code Reusability: You can create modular components in separate files and include them wherever needed.
• 2.     Improved Maintainability: Breaking down your code into smaller, manageable files can make it easier to maintain and understand.
• 3.     include only generates a warning, i.e., E_WARNING, and continue the execution of the script.

 

Example:

Filename : main.php

<?php

// content of main.php

include 'header.php';

echo "<p>This is the main content of the page.</p>";

include 'footer.php';

?>

In this example, when main.php is executed, it includes the contents of header.php, displays some content, and then includes the contents of footer.php. This way, you can structure your code in a more organized and reusable manner.

 

PHP require

PHP require is similar to include, which is also used to include files. The only difference is that it stops the execution of script if the file is not found whereas include doesn't.

Syntax

There are two syntaxes available for require:

require 'filename';  

Or   

require ('filename');  

Functionality:

• 1.     The require statement includes the specified file (filename.php) at the point where it's written in the code.
• 2.     It executes the code in the included file as if it were part of the main file.
• 3.     If the file is not found or there is an error during inclusion, a fatal error is issued, and the script terminates.

Use Cases:

• 1.     When including essential files that are critical for the operation of your script, and you want to ensure that their presence and correctness are mandatory.
• 2.     require generates a fatal error, i.e., E_COMPILE_ERROR, and stop the execution of the script.

Example:

<?php

// content of main.php

require 'header.php';

echo "<p>This is the main content of the page.</p>";

require 'footer.php';

?>

In this example, when main.php is executed, it requires the contents of header.php, displays some content, and then requires the contents of footer.php. If any of these files is missing or contains an error, it will result in a fatal error, ensuring that the necessary components are present for the script to run successfully.

PHP include vs PHP require

1.     Both include and require are same.

2.     But if the file is missing or inclusion fails, include allows the script to continue but require halts the script producing a fatal E_COMPILE_ERROR level error.

3.     Unlike include, if the specified file is not found or there is an error during inclusion with require, it results in a fatal error, and the script execution stops. This makes require more strict in its handling of file inclusions.

 

In summary, PHP's file inclusion feature is a valuable tool for creating organized, reusable, and maintainable code, ultimately improving the efficiency of web development projects.