def ip_quad_to_numstr(quad):
    """
    Convert an IP address string (e.g. '192.168.0.1') to an IP
    number as a base-10 integer given in ASCII representation.

    >>> ip_quad_to_numstr('192.168.0.1')
    '3232235521'
    """
    bytes = map(int, quad.split("."))
    packed = struct.pack('BBBB', *bytes)
    return str(struct.unpack('>L', packed)[0])