[date_time] Creating a ptime from a double

[Ryan McConnehey]

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?

Ryan
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[Igor R]

> 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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[Ryan McConnehey]

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

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[Igor R]

> 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.

Sorry, of course, you have to multiply the fractional part by some
factor (1000000?)
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[Ryan McConnehey]

Igor R wrote:

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.
    

Sorry, of course, you have to multiply the fractional part by some
factor (1000000?)
  

That makes more sense.  Thanks.

Ryan

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