String negative indices?

[George Sakkis]

drtimh... at comcast.net wrote:

> I'm just starting out on Python, and am stumped by what appears an oddity in the way negative indices are handled.
>
> For example, to get the last character in a string, I can enter "x[-1]". To get the 2nd and 3rd to last, I can enter x[-3:-1] etc. This is fine.
>
> Logically, I should be able to enter x[-2:-0] to get the last and next to last characters. However, since Python doesn't distinguish between positive and negative zero, this doesn't work. Instead, I have to enter x[-2:].
>
> With simple constants, this is ok, but it's a little more annoying when the start and end of the range are in variables somewhere. The only way I can find of making this work without lots of special-case "if" logic is to translate negative subscripts to positive, which kinda defeats the purpose of the negative subscripts anyway.
>
> Is there some magic I'm missing here? Wouldn't it actually be better for Python to treat 0 as a special case here, so that x[-2:0] and x[-2:] generated the same result?
>
> --Tim

x[-2:None]

I'm not sure if it qualifies as "magic" but you're right, it's not more
obvious than 0 would be.

George