1-hour offset in time string conversion

Question

Dennis on 24 Oct 2014

0
Link

Direct link to this question

https://au.mathworks.com/matlabcentral/answers/159906-1-hour-offset-in-time-string-conversion

Answered: Dennis on 3 Nov 2014

Hi there, I'm having trouble in converting string to datenum values. Somehow, there will be an offset of one hour when converting back to datestr. So, here is my example:

>> timestr = '1986-03-13T11:59:58.000Z';
>> test = datenum(timestr,'yyyy-mm-ddTHH:MM:SS.000Z')
     test =
       7.2544e+05
>> datestr(test,'yyyy-mm-ddTHH:MM:SS')
     ans =
       1986-03-13T12:59:58

To me, this seems pretty weird. I might be missing something very simple, though. I'd be glad if any of you could help me! Thanks

Dennis

1 Comment
Show -1 older commentsHide -1 older comments

Star Strider on 24 Oct 2014

I suggest you report this as a bug, specifically because in R2014b I get an even weirder result from running your code:

1986-03-13T04:59:58

a -19 hour error!

Sign in to comment.

Sign in to answer this question.

Answer 1

Peter Perkins on 31 Oct 2014

1
Link

Direct link to this answer

https://au.mathworks.com/matlabcentral/answers/159906-1-hour-offset-in-time-string-conversion#answer_157275

Dennis, I'm guessing you're somewhere in Europe, and that Star Strider is somewhere in the western US. As in, UTC+1 and UTC-7.

Reason is, the Z in your string is being treated as "Zulu", i.e., UTC, and the datenum is converted to your local time zone. Z has never (far as I know) been documented as something you could put in a date format for datestr. Prior to R2013a, this threw an error.

I'm not sure what you need to do with a date string like this. You may simply want to ignore the Z and preserve the time stamp itself. If they all have a trailing 'Z', I recommend just stripping that off.

If you have access to R2014b, you might consider using the new date and time features. For example:

>> timestr = '1986-03-13T11:59:58.000Z'
timestr =
1986-03-13T11:59:58.000Z
>> datetime(timestr,'Format','yyyy-MM-dd''T''HH:mm:ss.SSSXXX','TimeZone','UTC')
ans = 
   1986-03-13T11:59:58.000Z
>> datetime(timestr,'Format','yyyy-MM-dd''T''HH:mm:ss.SSSXXX','TimeZone','Europe/Paris')
ans = 
   1986-03-13T12:59:58.000+01:00
>> datetime(timestr,'Format','yyyy-MM-dd''T''HH:mm:ss.SSS''Z''')
ans = 
   1986-03-13T11:59:58.000Z