What are the best PHP input sanitizing functions?

Question

I am trying to come up with a function that I can pass all my strings through to sanitize. So that the string that comes out of it will be safe for database insertion. But t

Answer 1

what about this

$string = htmlspecialchars(strip_tags($_POST['example']));

or this

$string = htmlentities($_POST['example'], ENT_QUOTES, 'UTF-8');