How can PHP developers ensure that form input and direct URL input both work correctly for search functionality?

PHP developers can ensure that form input and direct URL input both work correctly for search functionality by checking if the search query exists in both `$_POST` and `$_GET` superglobals. If the query exists in `$_POST`, use that value for the search. If not, check `$_GET` for the query. This way, the search functionality will work seamlessly whether the user submits the search query through a form or directly through the URL.

$search_query = isset($_POST['search']) ? $_POST['search'] : (isset($_GET['search']) ? $_GET['search'] : '');

// Use $search_query for search functionality