Newbie question: Explain this behavior

[Ross Wilson]

On Thu, 14 Jul 2005 15:46:40 -0700, David Smith wrote:

> Why does code snippet one work correctly, but not two.  The only
> difference is the placement of the "else".  I know that indentation
> affects execution, but how does it change behavior in the following
> examples?  Thank you.
> 
> 1. 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'
<snip>

A quote from "Python: Essential Reference (2/e)" (p56) says it best:

"The 'else' clause of a loop executes only if the loop runs to completion.
This either occurs immediately (if the loop wouldn't execute at all) or
after the last iteration.  On the other hand, if the loop is terminated
early using the 'break' statement, the 'else' clause is skipped."

Ross