In PHP, how do I validate strings with SPL?

In PHP, you can use the SPL to validate strings by leveraging various built-in functionalities. This includes using SPL implementations to ensure that strings meet certain criteria.


        <?php
        $inputString = "Hello, World!";
        
        // Validate string length
        if (strlen($inputString) >= 5 && strlen($inputString) <= 20) {
            echo "Valid string length.";
        } else {
            echo "Invalid string length.";
        }

        // Validate string contains only alphabets
        if (ctype_alpha(str_replace(' ', '', $inputString))) {
            echo "The string contains only letters.";
        } else {
            echo "The string contains invalid characters.";
        }
        ?>