public static function isValidHostname($hostname)
    {
        if (defined('FILTER_VALIDATE_DOMAIN')) {
            $isValid = filter_var($hostname, FILTER_VALIDATE_DOMAIN, FILTER_FLAG_HOSTNAME);
        } else {
            // (less accurate) fallback for PHP < 7.0
            $isValid = preg_match('/^[a-z0-9_-]+(\.[a-z0-9_-]+)*$/i', $hostname);
        }

        if ($isValid) {
            return true;
        } else {
            throw new \RuntimeException(
                sprintf(Resources::INVALID_CONFIG_HOSTNAME, $hostname)
            );
        }
    }
public static function isValidHostname($hostname)
    {
        if (defined('FILTER_VALIDATE_DOMAIN')) {
            $isValid = filter_var($hostname, FILTER_VALIDATE_DOMAIN, FILTER_FLAG_HOSTNAME);
        } else {
            // (less accurate) fallback for PHP < 7.0
            $isValid = preg_match('/^[a-z0-9_-]+(\.[a-z0-9_-]+)*$/i', $hostname);
        }

        if ($isValid) {
            return true;
        } else {
            throw new \RuntimeException(
                sprintf(Resources::INVALID_CONFIG_HOSTNAME, $hostname)
            );
        }
    }
public static function isValidHostname ( $ hostname ) { if ( defined ( 'FILTER_VALIDATE_DOMAIN' ) ) { $ isValid = filter_var ( $ hostname , FILTER_VALIDATE_DOMAIN , FILTER_FLAG_HOSTNAME ) ; } else { // (less accurate) fallback for PHP < 7.0 $ isValid = preg_match ( '/^[a-z0-9_-]+(\.[a-z0-9_-]+)*$/i' , $ hostname ) ; } if ( $ isValid ) { return true ; } else { throw new \ RuntimeException ( sprintf ( Resources :: INVALID_CONFIG_HOSTNAME , $ hostname ) ) ; } }
Throws an exception if the string is not of a valid hostname.

@param string $hostname String to check.

@throws \InvalidArgumentException

@return boolean
Throws an exception if the string is not of a valid hostname .