On Mon, Nov 24, 2014 at 12:32 PM, boB Stepp <robertvst...@gmail.com> wrote: > Python 2.7.8 > Win7Pro > >>>> str = "0123456789" >>>> str[-1] > '9' >>>> str[-3:-1] > '78' >>>> str[-3:] > '789' > > I understand that the above is "the way it is" in Python, but I am > puzzled why the designers did not choose that str[-3:-1] returns > '789', especially since str[-1] returns '9'. What is the reason for > choosing Python's actual behavior?
For the same reason as this behavior with positive indices: >>> s = '0123456789' >>> s[1] '1' >>> s[3] '3' >>> s[1:3] '12' Here's what you can do with it: >>> s[-5:-3] + s[-3:-1] == s[-5:-1] True >>> len(s[-5:-3]) == -3 - -5 True Think of slicing as "everything from this index (-3) up to but not including (:) this index (-1)". Have I clarified or muddied it for you? :) Regards, -- Zach _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
