What are the best practices for validating form data in PHP?

Validating form data in PHP is crucial to ensure that the data submitted by users is correct and safe to use. Some best practices for validating form data in PHP include using functions like `filter_var()` to validate email addresses, using `preg_match()` to validate specific patterns like phone numbers or zip codes, and using `htmlspecialchars()` to prevent XSS attacks by sanitizing user input. 

// Example of validating an email address using filter_var()
$email = $_POST['email'];

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    // Email is valid
} else {
    // Email is invalid
}

Keywords

filter_var htmlspecialchars validation input sanitization error handling

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