Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Tue, 16 Apr 2013 16:05:55 -0500

Hi Eric,

On 2013-04-16 Eric Norum wrote:
> I'm trying to convert an EPICS time stamp into a string -- but in UTC, not
> the local time zone.

> The resultant string is one hour off.  It's as if the routines above are
> trying to apply daylight savings time correction to UTC.

I'm not sure if this is the source of your problem, but there is one very 
subtle gotcha about the ANSI epoch (1 Jan 1970) that I discovered years ago 
which might contribute to it: On that date, the UK was actually observing 
daylight savings time, so the local time in London was *not* the same as UTC.

It's also possible that the epicsTimeToGMTM() routine that you're using has a 
bug in it, there is no explicit test for it in libCom/test and I doubt if it's 
had very much real-world usage.

BTW %T is not portable; IIRC vxWorks and Windows do not support it, so don't 
use it in anything that might run there.

HTH,

- Andrew
-- 
It is difficult to get a man to understand something, when his salary
depends upon his not understanding it. -- Upton Sinclair

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System