a good explanation

John Machin sjmachin at lexicon.net
Thu May 25 14:40:19 CEST 2006

On 25/05/2006 9:27 PM, s99999999s2003 at yahoo.com wrote:
> hi
> my friend has written a loop like this
> cnt = 0
> files = [a,b,c,d]
> while cnt < len(files) :
>    do_something(files[cnt])
> i told him using
> for fi in files:
>    do_something(fi)
> is better, because the while loop method makes another call to
> len..which is slower..
> am i partly right? or is there a better explanation for using the for
> method.?

You are partially right.
More reasons:
(1) It's more elegant; you don't have the "cnt" if you don't need it, 
there's no extraneous evaluation of len(files).
(2) You don't get the chance to omit cnt += 1, like your friend did 

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