[Tutor] Python challenge and decryption

[Steven D'Aprano]

Joaquim Santos wrote:

>  - How can I make this "Human readable"? ... Print the letters in just one
> (or more) lines and maybe replace the " for spaces (This one I suppose it
> could/should be done with whitespaces() or just making a loop to check and
> change those for ' '.)


Firstly, you should not directly print anything in the function. You should 
always separate *functionality* from *presentation*. The function should do 
the job of doing the Caesar shift, and should return a string. This allows the 
caller to store the result in a variable for further work. Presentation should 
be handled by the caller, often (but not always) by using print.

So you should accumulate each character into a list, then when done combine 
all the characters together into a string using ''.join(the_list), and finally 
return the string.

Secondly, Caesar decryption should wrap around -- that is, it should only 
apply to letters A...Z and only produce letters A...Z, and likewise for 
lowercase. Anything not a letter shouldn't be shifted.

So it isn't enough to just add the shift to the letter. E.g. 'z' shifted by 1 
gives '{', but needs to be 'a'.

If you have trouble implementing these two concepts, don't hesitate to ask for 
additional hints and suggestions.



-- 
Steven