Python 3.7 Bug

[Terry Reedy]

On 3/25/2019 8:14 AM, 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 result is  0, then this just prints useless 0 - 0 - 1

>   if len(str(result)) == 1:
>    print(" --- DONE ---")
>    return "DONE"
>   else:
>    per(result, steps)

This function, properly written, was recently the subject of a youtube 
math video.  The largest known # of steps is 11.  Did you get it from 
there?


> 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?
> 
> Thanks,
> Bassam
> 


-- 
Terry Jan Reedy