On Fri, 27 Jun 2014 15:28:41 -0700, Hardee, Chuck wrote: > >But, what if the local time is 01:59? One would subtract the signed UTC >adjustment from the local time and then??? So, 01:59 - (-05:00) = 06:59, but >what about Daylight Savings Time? The current local time being adjusted is not >with the DST range, but the adjusted time via the UTC adjustment value is. >Does DST come into play here? Is the decision based on the local time or the >resulting UTC time? > Paradigm shift. Think of EST and EDT as two different time zones; EST with an offset of -5 hours; EDT with an offset of -4 hours.
Determine whether the time to be converted is EST, in which case subtract -5 hours; or EDT, in which case subtract -4 hours. (You seem to be OK in dealing with subtracting a negative number.) The result is UTC; no further decision is necessary. Eschew the term "adjusted time"; it adds to your confusion; think only of EST, EDT, and UTC. >A similar question comes into play on the other end of the DST range. If the >local time is prior to the end of the DST range, does one subtract 1 hour from >the adjusted time? > And, as others have said, that question can not be resolved without further information; it's truly ambiguous, which is probably one of your vendor's motivations for switching to UTC, which has no such problem. And UTC has no Daylight saving time. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
