Re: [Boost-users] [date_time] Creating a ptime from a double

Subject: Re: [Boost-users] [date_time] Creating a ptime from a double
From: Ryan McConnehey (mccorywork_at_[hidden])
Date: 2009-11-03 11:23:38

Igor R wrote:
> > A lot of the constructors of ptime deals with getting the current system time or time structures.  I have a double with the seconds and fractional microseconds from midnight January 1, 1970.  What is the best way to create a ptime object from this double?
> >   
>
>
> #include <boost/date_time/posix_time/posix_time.hpp>
> #include <math.h>
> namespace pt = boost::posix_time;
>
> int main()
> {
> 	double d = 1000.1;
> 	double sec;
> 	double mksec = std::modf(d, &sec);
> 	pt::ptime t = pt::from_time_t(static_cast<int>(sec)) +
> pt::microseconds(static_cast<int>(mksec));
> }
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The documentation for modf states that d == sec + mksec.  This means
that
mksec is a fractional number and not a whole number.  The
pt::microseconds expects whole numbers of microseconds.  If I
static_cast the fractional number I would get at most 1 when it
rounds.  Isn't this correct?

Ryan