How can the use of htmlentities() or htmlspecialchars() impact the handling of special characters in PHP forms?

Using htmlentities() or htmlspecialchars() in PHP forms can help prevent cross-site scripting (XSS) attacks by converting special characters like <, >, ", ', and & into their HTML entities. This ensures that user input containing these characters is displayed as text on the webpage rather than being interpreted as HTML or JavaScript code. It is important to apply these functions to any user input that is displayed on a webpage to enhance security.

// Example of using htmlentities() to handle special characters in a PHP form
$user_input = "<script>alert('XSS attack!')</script>";
$clean_input = htmlentities($user_input);

echo $clean_input;