C++ Time handle library: glibmm?

[Tomek <int inet24 pl>]

Hi there ;)

I'm looking for the C++ library having implemented two functionalities:
1. Basing on date and time I need to get number of seconds from the
1.1.1970.
2. Time (hh:mm) add and sub functions, i.e I'd like to add 45 minutes to
07:38 (this is quite simple to do witout the library) and also to be
able to calculate 12:38 minus 08:41.

In glibmm I found only GTimeVal struct, which is too accurate for me
(operates on miliseconds) and actually those functions don't solve my
problems.

Do you know any library having those functionalities?

P.S. I'm writing to this mailing list since glibmm is closely connected
to gtkmm.

Regards,
Tomek