[Tutor] Range within a range
bob gailer
bgailer at gmail.com
Fri Apr 11 21:30:23 CEST 2014
On 4/11/2014 1:13 PM, Andoni Gorostiza wrote:
> Hi tutor. I need your help with something I don't understand. In the
> tutorial, it mentions an example of a range within a range. I'll keep
> it simplified. How exactly does this work? I'll provide a few examples.
>
> >>> for x in range(0,5):
> ...for n in range(0,5):
> ... print(x)
>
> >>> for x in range(0,5):
> ...for n in range(0,5)
> ... print(n)
>
> This one comes from the tutorial:
>
> >>>for n in range(2, 10):
> ... for x in range(2, n):
> ... if n % x == 0:
> ... print(n, 'equals', x, '*', n//x)
> ... break
> ... else:
> ... # loop fell through without finding a factor
> ... print(n, 'is a prime number')
> ...
> 2 is a prime number
> 3 is a prime number
> 4 equals 2 * 2
> 5 is a prime number
> 6 equals 2 * 3
> 7 is a prime number
> 8 equals 2 * 4
> 9 equals 3 * 3
> Can you explain what is going on?
We could but that will not help you learn. Instead I recommend with
pencil and paper you play computer - "execute" (write) the code one step
at a time and write down what happens. Very simple example:
execute: change:
for x in range(0,2): x == 0
for n in range(0,2): n == 0
print(x) output == 0
next for n n == 1
print(x) output == 0
next for x x == 1
for n in range(0,2): n == 0
print(x) output == 1
keep going - at each step write what executes and what changes or happens
When you run into an operation you don't understand stop and either
- look it up
- ask this list
More information about the Tutor
mailing list