Simple slicing question

[Peter Hansen]

"Nikhil R. Deshpande" wrote:
> 
> Python 2.2 (#28, Dec 21 2001, 12:21:22) [MSC 32 bit (Intel)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
> >>> a = [1, 2, 3]
> >>> a[100:200]
> []
> 
> Why doesn't a[100:200] result in an IndexError?

The other answers are all wonderful, but I want to point out
that the values 100 and 200 in a[100:200] are *not* indices,
and therefore an IndexError should definitely not be thrown.

In the expression a[100] you are selecting the hundred-and-first
element (starting from zero, of course), and that's an index.

In a[100:200] you are selecting everything *between* the 
hundredth and two-hundredth elements, not both of those
elements.

You might argue for a SliceError, but not an IndexError.