Python indentation deters newbies?

[Jorge Godoy]

"beliavsky at aol.com" <beliavsky at 127.0.0.1:7501> writes:

> Jorge Godoy <godoy at ieee.org> wrote:
>
>>Just an attempt and trying to keep it like your code. 
>
> Thanks. My code did not correctly illustrate breaking out of more than one
> level of loop. How would the following code be translated to Python?

For that I'd adopt either the use of exceptions or a flag. ;-)

> It is silly of course, but real-world situations where you want to exit a
> nested loop are not that rare.
>
> program xnest_loop
> ! illustrate breaking a nested loop
> integer :: i,j,k,n
> n = 4
> ido: do i=1,n
>    jdo: do j=1,n
>       if (i+j > n) exit ido
>       do k=1,n
>          if (i+j-k < 0) exit jdo
>          print*,i,j,k
>       end do
>    end do jdo
> end do ido
> end program xnest_loop
>
> output:
>  1 1 1
>  1 1 2
>  2 1 1
>  2 1 2
>  2 1 3
>  3 1 1
>  3 1 2
>  3 1 3
>  3 1 4

>>> n = 4
>>> for i in xrange(1, n):
...     for j in xrange(1, n):
...             if (i + j > n): exit
...             for k in xrange(1, n):
...                     if ((i + j - k) < 0):
...                             to_exit = 1
...                             break
...                     print i, '\t', j, '\t', k
...             if to_exit:
...                     break
...
1       1       1
1       1       2
2       1       1
2       1       2
2       1       3
3       1       1
3       1       2
3       1       3
>>>


Is your last line (3 1 4) correct?  In the expression "3 + 1 - 4 < 0" it
is true, so I think the line should be printed...  Should it? (Does the
loop run at least once before evaluating the expression?)  I really
haven't paid attention to your code, just "translated" it to the above
python, with the same logic as the previous one.  Using exceptions would
give me a finer grained control, I think, but would require more lines
of code.



Be seeing you,
-- 
Godoy.     <godoy at ieee.org>