How can PHP require_once statements improve code efficiency and prevent errors in file inclusion?

Using PHP require_once statements can improve code efficiency and prevent errors in file inclusion by ensuring that a file is only included once in a script. This prevents issues such as redeclaring functions or classes multiple times, which can lead to errors. By using require_once, you can guarantee that a file is included only once, reducing the risk of conflicts and improving the overall organization of your code.

require_once 'config.php';
require_once 'functions.php';
require_once 'classes/Database.php';