Include and Required in php with syntax and examples

Include and require are used to insert the contents of one PHP file into another. This allows for reusable code, easier maintenance, and organization.

Include:

Syntax: include 'filename.php';

Example:

// header.php
echo "Header Content";

// index.php
include 'header.php';
echo "Main Content";


Require:

Syntax: require 'filename.php';

Example:

// footer.php
echo "Footer Content";

// index.php
require 'footer.php';
echo "Main Content";


Key differences:

- Include:
    - Generates a warning if the file is not found
    - Script continues execution
- Require:
    - Generates a fatal error if the file is not found
    - Script terminates execution

Return Statement:

- Include and require can return values from the included file
- Use the return statement in the included file

Example:

// config.php
return array('db_host' => 'localhost', 'db_user' => 'root');

// index.php
$config = include 'config.php';
print_r($config);


Best Practices:

1. Use include for optional files
2. Use require for essential files
3. Use absolute paths for file inclusion
4. Avoid using include or require inside loops
5. Use autoloading for classes and functions

By understanding include and require, you can effectively organize and reuse code in your PHP applications.