Dick Moores wrote:
> from datetime import datetime
>
> print "Enter 2 dates, first the earlier date, then the later date."
> def getDate():
> date = raw_input("Enter date as month/day/year, or enter nothing for
> today: ")
> if date == "":
> date = datetime.now()
> print "Today's date entered"
> else:
> date = datetime.strptime(date, '%m/%d/%Y')
> return date
>
> print "What's the earlier date?"
> date1 = getDate()
> print
> print "What's the later date?"
> date2 = getDate()
> print
> print "The difference between the dates is", (date2 - date1).days, 'days'
>
> However, when the earlier date (date1) is today's date entered by just
> pressing Enter, the result is always 1 day too small. And I don't see
> how to correct this, other than by adding the 1 (and I'd have to give up
> using a function, I think). I still don't really get datetime. Help?
It's a rounding error.
In [3]: from datetime import datetime
In [4]: n=datetime.now()
In [5]: n
Out[5]: datetime.datetime(2008, 4, 17, 8, 2, 15, 278631)
Notice n has a time component.
In [8]: y=datetime.strptime('4/18/2008', '%m/%d/%Y')
In [14]: y
Out[14]: datetime.datetime(2008, 4, 18, 0, 0)
y represents midnight on the given date.
In [9]: y-n
Out[9]: datetime.timedelta(0, 57464, 721369)
So y-n is a fractional day, not a whole day.
You could either create n with hours=minutes=0, or round the difference
up to the next whole number of days.
Kent
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