How can PHP version affect the functionality of require and include statements?

PHP version can affect the functionality of require and include statements because the behavior of these statements may change between different PHP versions. To ensure compatibility across different PHP versions, it is recommended to use the `__DIR__` magic constant along with the `DIRECTORY_SEPARATOR` constant to build the correct file path when using require and include statements.

require __DIR__ . DIRECTORY_SEPARATOR . 'path/to/file.php';