Stepping backwards in for loop?
Steve Holden
sholden at holdenweb.com
Sun Apr 15 11:28:12 EDT 2001
"Andrew Dalke" <dalke at acm.org> wrote in message
news:9banud$ge$1 at slb6.atl.mindspring.net...
> Carlos Ribeiro wrote:
> >It would be a *lot* easier if strings had a reverse method, or if the
> >reverse() methods returned the reversed string. However, similarly to
> >sort(), the Python-way-of-doing-things must have some good reason for
> >reverse() to behave this way (as a inplace operation on the list).
>
> Lists have a reverse method because lists are mutable.
> Consider strings as more akin to tuples. Both are immutable.
>
But there's no good reason why there shouldn't be a "reverse" function which
returns the reverse of any sequence, surely? The question then becomes
whether a built-in function could improve on the efficiency of
>>> def sreverse(s):
... l = list(s)
... l.reverse()
... return "".join(l)
...
>>> sreverse("abcdefg")
'gfedcba'
I'd be very surprised if it couldn't ... though then there's Unicode to take
into account.
regards
STeve
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