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Re: Understanding dotimes skipping by 2
From: |
Tim Johnson |
Subject: |
Re: Understanding dotimes skipping by 2 |
Date: |
Thu, 27 Sep 2018 15:32:07 -0800 |
User-agent: |
Mutt/1.10.0 (2018-05-17) |
* Marco Wahl <marcowahlsoft@gmail.com> [180927 15:16]:
> Tim Johnson <tim@akwebsoft.com> writes:
>
> > the following code snippet is as follows:
> > (setq l `(1 2 3 4 5 6 7 8 9 0))
>
> > ;; iterate through a list two elements at a time
> > (let ((x 0))
> > (dotimes (/ (length l) 2)
> > (progn
> > (insert (format "%s %s, " (nth x l) (nth (+ x 1) l)))
> > (setq x (+ x 2)))))
> >
> > ;; and below are the results
> > 1 2, 3 4, 5 6, 7 8, 9 0, nil nil, nil nil, nil nil, nil nil, nil nil, 2
> >
> > I'm confused about the output (nil etc...)which follow the expected
> > numbers.
> > could someone explain?
> > P.S. I get the same output without the `progn form
>
> Looks like "/" is a variable which gets bound to the values of 0 up to
> (length l) and the result of the loop is 2.
>
> It's in the documentation (C-h f dotimes).
You've revealed that I have a syntax error in the code above.
`/ was being treated as a variable
I needed an outer parens for the arguments and needed to add a
count variable.
;;
(dotimes (count (/ (length l) 2)) ;; what I'm after (I think)
> HTH
Thanks, helpful indeed
--
Tim Johnson
http://www.tj49.com
Re: Understanding dotimes skipping by 2, Marco Wahl, 2018/09/27