On Tue, Aug 20, 2013 at 05:20:23PM +0800, sikonai sikonai wrote: > >>> list=[1,2,3,4,5,6,7,8,9] > >>> list[9:0:-2] > [9, 7, 5, 3] > >>> list[10:0:-2] > [9, 7, 5, 3] > > I want to know whether they have some difference.
Consider: 2+2 2*2 2**2 All three give the same result, 4, and yet they are different. You can see that they are different, because if you change the numbers from 2 to something else, the results will no longer be the same: 3+3 3*3 3**3 No longer equal! This proves that + * and ** are not the same thing. Go back to your example: L = [1, 2, 3, 4, 5, 6, 7, 8, 9] It turns out that L[9:0:-2] happens to be the same as L[10:0:-2], but that is only because the list only has 9 items. But if you do this: L = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15] for example, and then compare L[9:0:-2] and L[10:0:-2], you will see they are quite different: py> L = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15] py> L[9:0:-2] [10, 8, 6, 4, 2] py> L[10:0:-2] [11, 9, 7, 5, 3] -- Steven _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
