What are some potential pitfalls when using PHP for a Primzahlchecker program?

One potential pitfall when using PHP for a Primzahlchecker program is not properly validating user input, which can lead to security vulnerabilities such as SQL injection attacks. To solve this issue, always sanitize and validate user input before using it in your PHP code.

// Sanitize and validate user input for Primzahlchecker program
$num = isset($_POST['num']) ? intval($_POST['num']) : 0;