Python 3.7 Bug
Peter Otten
__peter__ at web.de
Mon Mar 25 14:27:14 EDT 2019
Bassam Abdul-Baki wrote:
> Greetings,
>
> In the following code, there's a bug on certain parameters.
>
> ----------
>
> def per(n, steps = 0):
> digits = [int(i) for i in str(n)]
> result = 1
> for j in digits:
> result *= j
> steps += 1
> print(steps, result, sep=" - ")
> if result == 0:
> print(result, str(result), len(str(result)), sep=" - ")
> if len(str(result)) == 1:
> print(" --- DONE ---")
> return "DONE"
> else:
> per(result, steps)
An indent of four spaces per level would make this much easier to read.
> What the program does:
> If I run per(X) and X is a multiple of 10, I should end up with 0 in a
> finite amount of steps.
>
> The problem:
> If I run per(54), I do not get 'DONE' printed through the return
> statement. WRONG!
>
> If I run per(20), I do get 'DONE' printed through the return statement.
> CORRECT!
>
> 20, 30, etc. are correct. 25, 45, etc. are not.
>
> Is this a bug?
If you write a function that does not do what you want it to do -- then, yes
that is a bug ;)
If I were to guess: You expect that line to return "DONE":
> per(result, steps)
However, in Python you need to be explicit:
return per(result, steps)
will return the result of the recursive call.
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