Is it necessary to use htmlentities() or htmlspecialchars() when processing form inputs in PHP to prevent issues with special characters like "<" and ">" appearing in variables?

When processing form inputs in PHP, it is important to use htmlentities() or htmlspecialchars() to prevent issues with special characters like "<" and ">". These functions encode special characters into HTML entities, ensuring that the input is safely displayed in the browser and preventing potential security vulnerabilities like cross-site scripting (XSS) attacks.

// Using htmlentities() to encode special characters in form input
$input = $_POST['input'];
$safe_input = htmlentities($input);

// Using htmlspecialchars() to encode special characters in form input
$input = $_POST['input'];
$safe_input = htmlspecialchars($input);