Using time_duration::rep_type::ticks_per_second

16 May 2003

      I have written a function to convert a posix_time::ptime to a windows
FILETIME (which is in essence a 64-bit value counting 100-nanosecond
intervals since Jan 01, 1601). 

In order to do so, I do a time difference between
the ptime and a time setup to the FILETIME reference time. To convert
from this time_duration to the FILETIME count, I use
time_duration::rep_type::ticks_per_second. Since this does not seem to
be documented I just wanted to make sure I was using it correctly (or
if I should be using it at all). Here is my code (which seems to work):

const ULONGLONG nanosecPerFileTimeUnit = 100;

using namespace boost::posix_time;
using namespace boost::gregorian;
FILETIME toFileTime
(
    const ptime& time
)
{
    ptime refTime(date(1601,Jan,01));

    time_duration sinceRefDate = time - refTime;

    ULARGE_INTEGER durationInFileTimeUnits;
    const ULONGLONG timeDurTicksPerSec =
time_duration::rep_type::ticks_per_second;

    const ULONGLONG fileTimeUnitsPerTimeDurTick = 
(nanosecPerSec/timeDurTicksPerSec) / nanosecPerFileTimeUnit;

    durationInFileTimeUnits.QuadPart =
sinceRefDate.ticks()*fileTimeUnitsPerTimeDurTick ;

    FILETIME ft;
    ft.dwLowDateTime = durationInFileTimeUnits.LowPart;
    ft.dwHighDateTime = durationInFileTimeUnits.HighPart;

    return ft;
}

Using time_duration::rep_type::ticks_per_second

d_zakaib