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incrementing a time tuple by one day

Donn Cave donn at u.washington.edu
Thu Sep 23 15:06:31 EDT 2004 
In article <QcudnRWf360rm87cRVn-vg at powergate.ca>,
 Peter Hansen <peter at engcorp.com> wrote:
> David Stockwell wrote:
> > I'm sure this has been asked before, but I wasn't able to find it.
> > 
> > First off I know u can't change a tuple but if I wanted to increment a 
> > time tuple by one day what is the standard method to do that?
> > 
> > I've tried the obvious things and haven't gotten very far.
> > 
> > I have a time tuple that was created like this:
> > aDate = '19920228'
> > x = time.strptime(aDate,"%Y%m%d")
> > print x
> > (1992, 2, 28, 0, 0, 0, 4, 59, -1)
> > 
> > y = time.mktime(x) + time.mktime((0,0,1,0,0,0,0,0,0))
> > print y
> > 1643277600.0
> > print time.ctime(y)
> > 'Thu Jan 27 05:00:00 2022'
> > 
> > It appears to have decremented by a day and a month instead of increment.
> > 
> > What am I doing wrong?
> 
> What you're doing wrong is: not using the datetime module...
> 
>  >>> aDate = '19920228'
>  >>> x = time.strptime(aDate, '%Y%m%d')
>  >>> print x
> (1992, 2, 28, 0, 0, 0, 4, 59, -1)
>  >>> d = datetime.datetime.fromtimestamp(time.mktime(x))
>  >>> d
> datetime.datetime(1992, 2, 28, 0, 0)
>  >>> y = d + datetime.timedelta(days=1)
>  >>> y.ctime()
> 'Sat Feb 29 00:00:00 1992'


$ python
Python 2.2 (#1, 11/12/02, 23:31:59) 
[GCC Apple cpp-precomp 6.14] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import datetime
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
ImportError: No module named datetime
>>> 

Well, who knows, maybe datetime is the answer for him,
but if not, I would just use 24*60*60 instead of trying
to get one day in seconds out of mktime().  (I think if
you look at the date closer, it isn't decremented all!)

   Donn Cave, donn at u.washington.edu
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