How can PHP beginners effectively implement user input validation and sanitization when allowing users to add content like smileys to a website?

When allowing users to add content like smileys to a website, PHP beginners can effectively implement user input validation and sanitization by using functions like htmlspecialchars() to prevent XSS attacks and regex to validate input format. Additionally, they can use a whitelist approach to only allow specific characters or smileys to be entered. 

// Validate and sanitize user input for smileys
$user_input = $_POST['user_input'];

// Validate input format using regex
if (!preg_match('/^[a-zA-Z0-9\s\:\;\)\(\]\[&%$#@!]+$/', $user_input)) {
    die('Invalid input format');
}

// Sanitize input to prevent XSS attacks
$clean_input = htmlspecialchars($user_input, ENT_QUOTES, 'UTF-8');

// Whitelist approach to only allow specific smileys
$allowed_smileys = array(':)', ':(', ';)', ':D');
if (!in_array($clean_input, $allowed_smileys)) {
    die('Invalid smiley');
}

// Process the validated and sanitized input
// Add the user input to the website content

Keywords

PHP user input validation sanitization smileys website

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