[Tutor] Program for outputing the letter backward

[Kent Johnson]

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