Re: [Boost-users] Missing functions in date_time library

From: Sean Rohead (sean.rohead_at_[hidden])
Date: 2005-07-28 14:51:06

Just as a follow up to this, let me describe what I'm trying to do.  I
would like the current time in UTC with microsecond resolution.  Well,
the microsec_clock class only provides a local_time() method (unlike the
second_clock class which also provides universal_time()).  So, I need to
convert the result of local_time() into UTC but I can't since the only
class which knows the local timezone is c_local_adjustor and it does not
provide local_to_utc() (only utc_to_local()).

If there is a better way to get the current time in UTC with microsecond
resolution, I'd be happy to use it instead.

Thanks,

Sean

-----Original Message-----
I'm even more confused after looking at the URL and test file you
suggested.  All of the examples in those documents require you to
explicitly construct and provide a time zone using a name or an offset
from UTC.  I don't want to have to hardcode a timezone in my program --
I just want to use whatever time zone that the user has configured on
their computer.  The c_local_adjustor did this for me in 1.32 (although
as noted in my original email, it only solves half of the problem).
Perhaps I missed something in the URL you sent, but I didn't see
anything in there which simply uses the timezone in use on the local
machine.

Thanks,

Sean

On Fri, 22 Jul 2005 18:09:10 -0600, Sean Rohead wrote
> I am using the boost date_time library and noticed that there is a
> from_ftime() function to convert a FILETIME into a ptime, but I could 
> not find the reverse operation to_ftime().  Am I missing it somewhere?

No.  FILETIME, as you're certainly aware, is a Windows only way to
measure time.  This function is there primarily to support conversion
from legacy applications.  If there's really some need it's not hard to
support.

> Likewise, I am using the c_local_adjustor::utc_to_local() function and

> cannot find the corresponding local_to_utc() function in
c_local_adjustor.

In 1.33 there is vastly enhanced support for local time conversion via
the timezone class and it's friends posix_timezone and tz_database.  See

<http://engineering.meta-comm.com/resources/cs-win32_metacomm/doc/html/d
ate_time/local_time.html#date_time.local_time.time_zone_base>

for more on this.  If you still want to use the compile time approach
supported in 1.32, have a look at
libs/date_time/test/posix_time/testlocal_adjustor.cpp.   There's code in
there
that show how to convert back and forth.

Jeff

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