Re: [icu-support] DateTime formatting issues with pre-Gregorian dates

[Steven R. L. <sr...@ic...>]

Thanks. Would you mind filing a bug report?

El [FECHA], "[NOMBRE]" <[DIRECCIÓN]> escribió:

I've found what seems to be a workaround...

UDate ToICUDate(const DateTime& DateTime)
{
//const int64 UNIXTimestamp = DateTime.ToUnixTimestamp();
//return static_cast<double>(UNIXTimestamp) * U_MILLIS_PER_SECOND;

UErrorCode ICUStatus = U_ZERO_ERROR;

icu::GregorianCalendar GregCal(ICUStatus);
GregCal.setTimeZone(icu::TimeZone::getUnknown());

int32 Year, Month, Day;
DateTime.GetDate(Year, Month, Day);
GregCal.set(Year, Month - 1, Day, DateTime.GetHour(), DateTime.GetMinute(), DateTime.GetSecond());

return GregCal.getTime(ICUStatus);
}

The commented out code at the top is how we used to convert to a UDate (via a timestamp), however if I instead marshal the time through a icu::GregorianCalendar instance, I get back the UDate that ICU is expecting and pre-Georgian dates seemingly format correctly (even without having to change the calendar used by the icu::DateFormat).

I'm not terribly happy with this as a solution though, and I'd still like to know why the timestamp method is having issues as I don't believe our representation of time is that unusual.

-Jamie.

On 28 July 2016 at 00:49, Jamie Dale <jam...@gm...> wrote:
FWIW, before asking here I did try and search through the mailing list, and this post from 2006 kept cropping up: https://sourceforge.net/p/icu/mailman/message/12529106/

This is strikingly similar to what I'm seeing (1st Jan 0001 is 2 days off - I get 3rd Jan 0001), but given this is from 2006, surely it's been fixed by now?

-Jamie.

On 27 July 2016 at 23:40, Jamie Dale <jam...@gm...> wrote:
Hey all,

I'm investigating an issue where pre-Gregorian dates are failing to format correctly with icu::DateFormat.

We're using ICU 53, and our internal concept of time is ticks of 0.1 microseconds since 1st January 0001 - we convert this to a UNIX timestamp and multiply by U_MILLIS_PER_SECOND before passing it to ICU as a UDate.

At first I thought this might be due to the Gregorian switch-over, so I tried constructing my own icu::GregorianCalendar, setting the Gregorian change date to 1st January 0001, and then letting the icu::DateFormat adopt that as its calendar, however it didn't seem to make any difference (my calendar reports U_USING_FALLBACK_WARNING when being constructed... I'm not sure why).

I'm wondering if anyone else has seen this issue, or whether anyone has any advice?

Thanks,
Jamie.


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