kebab-style.php

<?php

echo toKebabStyle("TestingConversion");

function toKebabStyle($input) {
    $result = preg_replace_callback(
        '/([a-z])([A-Z])/',
        function ($match) use ($input) {
            return $match[1] . "-" . $match[2];
        },
        $input
    );
    return strtolower($result);
}