[Development] How does mktime() handle DST transitions ?

Kevin Kofler kevin.kofler at chello.at
Thu Nov 5 00:06:11 CET 2015

Welbourne Edward wrote:
> I'm looking into QTBUG-49008 and need to work out how diverse
> implementations of mktime handle DST transitions: at one end of the year
> there's a gap (where 1:59 is followed by 3:00), at the other end there's
> a duplicated hour (where 2:59 is followed by a reprise of 2:00 in
> Europe, or 1:59 by 1:00 in the USA, IIUC).  While we still need to work
> out what behaviour *we* want to give, implementing it is going to depend
> on knowing what the platform mktime gives us to work with.

The EU actually defines the switchover time in UTC, so which hour is 
duplicated depends on the actual time zone. It's the 3:mm hour in CET/CEST.

        Kevin Kofler

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