How can PHP developers ensure the security and integrity of their code when handling sensitive data like user inputs in forms?

To ensure the security and integrity of their code when handling sensitive data like user inputs in forms, PHP developers should sanitize and validate all user inputs to prevent SQL injection and cross-site scripting attacks. Additionally, they should use prepared statements when interacting with databases to prevent SQL injection vulnerabilities. Implementing input validation and output escaping techniques can help protect against security threats.

// Sanitize and validate user input from a form
$username = filter_var($_POST['username'], FILTER_SANITIZE_STRING);
$email = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);

// Use prepared statements to interact with the database
$stmt = $pdo->prepare("INSERT INTO users (username, email) VALUES (:username, :email)");
$stmt->bindParam(':username', $username);
$stmt->bindParam(':email', $email);
$stmt->execute();