[Tutor] Program for outputing the letter backward

Hoffmann oasf2004 at yahoo.com
Wed Mar 29 05:29:42 CEST 2006


--- Kent Johnson <kent37 at tds.net> wrote:

> Hoffmann wrote:
> > Hello:
> > 
> > I am trying to write a code (this is an exercose
> from
> > a book). The goal is to write a program that takes
> a
> > string  and outputs the letters backward, ine per
> > line.
> > Ok. I did a test first, by writing a code with
> > numbers:
> > 
> > a=0; b=10
> > while a<=b:
> >    print b
> >    b -= 1
> > 
> > Here the output is:
> > 10
> > 9
> > 8
> > 7
> > 6
> > 5
> > 4
> > 3
> > 2
> > 1
> > 0
> > That worked fine.
> > Now, back to my exercise. I tried to write a code
> that
> > takes the string 'car' as the input:
> > 
> > vehicle='car'
> > index = vehicle[-1]       #the last letter
> > index_zero = vehicle[0]   #the first letter
> > 
> > while index >= index_zero:
> >    letter=vehicle[index]
> >    print letter
> >    index -= 1
> 
> You are confusing the index of a letter - the number
> which represents 
> its position in the word - with the letter itself.
> In your code, index 
> and index_zero are actually letters, not indices.
> Try to rewrite the 
> code so they are numbers.
> > 
> > The problem is that I get no output here.
> 
> My guess is you got a TypeError on the line
>    letter=vehicle[index]
> 
> decause index is a letter. It's important to give us
> accurate 
> descriptions of what happens, and to show error
> messages and the 
> tracebacks that come with them. This can be very
> helpful when you have a 
> problem.
> 
> Kent
> 
> _______________________________________________

Hi Kent,

Sorry for not showing the traceback the first time.
Please, see it below:

Traceback (most recent call last):
  File "<stdin>", line 2, in ?
TypeError: string indices must be integers

Any hint?

Thanks,
Hoffmann

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