What best practices should PHP developers follow when handling user input validation and sanitization in web forms?

When handling user input validation and sanitization in web forms, PHP developers should always validate and sanitize user input to prevent security vulnerabilities such as SQL injection, cross-site scripting (XSS), and other forms of attacks. It is important to use built-in PHP functions like filter_var() or htmlspecialchars() to validate and sanitize user input before processing it in the application. 

// Example of validating and sanitizing user input in a web form
$user_input = $_POST['user_input'];

// Validate user input
if (filter_var($user_input, FILTER_VALIDATE_EMAIL)) {
    // Sanitize user input
    $sanitized_input = htmlspecialchars($user_input, ENT_QUOTES);
    
    // Process sanitized input
    // ...
} else {
    echo "Invalid email address";
}

Keywords

filter_input filter_var htmlentities htmlspecialchars validation

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