FW: Europe/Paris timezone bug

Rodrigo Severo rodrigo.lists at fabricadeideias.com
Mon Nov 17 13:35:35 UTC 2003

LIVINGSTON Alex wrote:

> Jason, Rodrigo, and others:
> I at first misunderstood Jason's explanation because he wrote 
> "...Daylight saving goes into effect..." when what he meant was 
> "...daylight saving goes out of effect..." or "...daylight-saving time 
> ends...", and I then didn't look at the dates in the following output.
> Rodrigo's explanation is correct, but it overlooks one thing: if the 
> device's clock is set to a time between 02:00 and 03:00 on the morning 
> that daylight saving ends, the behaviour described implies that the 
> device regards the time it is set to as being the first occurrence of 
> that time that night (as all times between 02:00 and 03:00 occur twice 
> on that night). What determines that?

It all depends on how do you set the clock. If you use mktime to create 
a time_t, the tm_isdst member of tm is the way to indicate if you are 
talking about the first or the second occurence of a given time between 
2:00am and 3:00am.

If you are already using a timestamp, there should be no doubt at all as 
the timestamp, being a number of seconds since epoch leaves no doubt 
about which 2:14am you are talking about.

> If, as I first imagined, the time of a device is set to 02:14 on the 
> morning daylight saving _starts_, a time that does not occur, what 
> happens then?

I have not tested it but I bet that it also depends on how you set the 
time. What are you using? What happened? Please report.

Rodrigo Severo

Rodrigo Severo
Fábrica de Idéias
Fone: +55(61)321 1357
Fax: +55(61)223 1712
SBS - Quadra 2 - Ed. Empire Center - Sala 1301
Brasília/DF - Brasil
CEP: 70.070-904

More information about the tz mailing list