Reversing a string

[Aahz]

In article <Xns99616C389BA94martinwilliamsdurkin at 130.133.1.4>,
Martin Durkin  <nospam at williamsdurkin.co.uk> wrote:
>aleax at mac.com (Alex Martelli) wrote in
>news:1i0kjpx.wjw44j15np22dN%aleax at mac.com: 
>>
>> So, something like:
>> 
>> for c in reversed(x): print c
>> 
>> is mostly likely how I'd present the solution to the task. 
>
>This is an interesting point to me. I am just learning Python and
>I wonder how I would know that a built in function already exists?
>At what point do I stop searching for a ready made solution to a
>particular problem and start programming my own function?  Is it just a
>matter of reading *all* the documentation before I start coding?

You should at least know that you can do:

l = list(s)
l.reverse()
for c in l:
    print c

This works in all versions of Python back to 1.5.2 IIRC.  reversed() is
a moderately new built-in function; I would agree with people who claim
that you should memorize most of the built-in functions (which is
precisely why there is a high barrier to adding more built-in functions).

But certainly if you're using a datatype you should make a point of
reading all its documentation, which would mean you'd know that list()
can convert any iterable type.
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

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