How can PHP beginners effectively test and debug regular expressions for form validation?

PHP beginners can effectively test and debug regular expressions for form validation by using online regex testing tools like Regex101 or RegExr. These tools allow users to input their regular expression pattern and test it against sample input data to see if it matches correctly. Additionally, beginners can use PHP's preg_match() function to test their regular expressions within their PHP code and debug any issues that may arise.

// Regular expression for email validation
$pattern = "/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/";

// Test email against the regular expression
$email = "example@example.com";
if (preg_match($pattern, $email)) {
    echo "Email is valid.";
} else {
    echo "Email is invalid.";
}