[Tutor] Counting a string backwards

[Alan Gauld]

On 28/05/17 18:58, C W wrote:

> Now if I do case 2,
>> print(great[-3:-1])
>> me
> 
> Where did the exclamation mark go in case 2?
> 
> I was told the count begins at zero, that's true going forward, but not
> backwards.

Its not about where the count starts its about where it finishes.
It finishes 1 item before the second index. so in this case
you get the items at -3 and -2.

If you specify a third parameter you can change the
direction of the count thus:

>>> great[-1:-3:-1]
'!e'

So now you get the characters at -1 and -2 (ie in reverse order)

If you want them in original order starting at -3 just omit
the -1:

>>> great[-3:]
'me!'

HTH,

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos