public function rtrim($str, $charlist = null)
    {
        return isset($charlist) ? rtrim($str, $charlist) : rtrim($str);
    }
public function rtrim($str, $charlist = null)
    {
        return isset($charlist) ? rtrim($str, $charlist) : rtrim($str);
    }
public function rtrim ( $ str , $ charlist = null ) { return isset ( $ charlist ) ? rtrim ( $ str , $ charlist ) : rtrim ( $ str ) ; }
right trim string

@param string $str
@param array $charlist
@return string
right trim string