How can PHP developers ensure the security of their code when working with user input in forms?

PHP developers can ensure the security of their code when working with user input in forms by properly sanitizing and validating the input data. This includes using functions like htmlspecialchars() to prevent XSS attacks, validating input against expected formats, and using prepared statements to prevent SQL injection attacks. 

// Sanitize user input using htmlspecialchars()
$user_input = htmlspecialchars($_POST['user_input']);

// Validate input against expected format
if (preg_match('/^[a-zA-Z0-9]+$/', $user_input)) {
    // Input is valid, proceed with processing
} else {
    // Input is not valid, handle error accordingly
}

// Use prepared statements to prevent SQL injection
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = ?");
$stmt->execute([$user_input]);

Keywords

SQL injection Cross-site scripting (XSS) htmlspecialchars prepared statements input validation

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