`substr` usage: ```php substr ( string $string , int $start [, int $length ] ) : string ``` ```php function startsWith($haystack, $needle) { $length = strlen($needle); return (substr($haystack, 0, $length) === $needle); } function endsWith($haystack, $needle) { $length = strlen($needle); if ($length == 0) { return true; } return (substr($haystack, -$length) === $needle); } ``` reference: - [stackoverflow](https://stackoverflow.com/questions/834303/startswith-and-endswith-functions-in-php) - [php documention](https://www.php.net/manual/en/function.substr.php)