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How can I convert a list to string so I can call insert or message with it? I need to display c-offsets-alist but I got Wrong type argument: char-or-string-p for insert or Wrong type argument: stringp for message.

jcubic
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5 Answers5

64

I am not sure of what you are trying to achieve, but format converts "stuff" to strings. For instance:

(format "%s" your-list)

will return a representation of your list. message uses format internally, so 

(message "%s" your-list)

will print it

juanleon
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    Probably better `%S` instead of `%s`, to print the list in Lisp syntax. –  Sep 24 '13 at 11:37
34

(format) will embed parentheses in the string, e.g.:

ELISP> (format "%s" '("foo" "bar"))
"(foo bar)"

Thus if you need an analogue to Ruby/JavaScript-like join(), there is (mapconcat):

ELISP> (mapconcat 'identity '("foo" "bar") " ")
"foo bar"
Alexander Gromnitsky
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10

Or 

(prin1-to-string your-string)

Finally something special

(princ your-string)
Andreas Röhler
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1
M-x pp-eval-expression RET c-offsets-alist RET
jcubic
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muede
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0

If you need to convert a list like ((a b c d e)) to a string "a b c d e" then this function might help:

(defun convert-list-to-string (list)
  "Convert LIST to string."
  (let* ((string-with-parenthesis (format "%S" list))
     (end (- (length string-with-parenthesis) 2)))
    (substring string-with-parenthesis 2 end)))
Evgeny Mikhaylov
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  • I don't want to get rid of parentheses I want to display a list or a tree as it is. If you have a list of strings and want to convert that to sting you have other options than substring. You can create a function to convert any type of string and use `(string-join (map 'symbol-name '(foo bar baz)) " ")` here I use `symbol-name` but it should be `any->string`. – jcubic May 02 '21 at 18:38
  • And your code will make no sense if you call it like this `(convert-list-to-string '(foo bar (baz (quux))))` I think that you should ask another question because this is not the answer to my question. – jcubic May 02 '21 at 18:41
  • This is just my solution, taking the answer of Alexander Gromnitsky and getting rid of parenthesis. I stumbled upon the problem of converting a list like ````((a b c d e))```` to a string ````"a b c d e"````. This works for me and I hope will help someone else. – Evgeny Mikhaylov May 03 '21 at 07:00
  • This looks like an answer to a different question, how to convert `((a b c d e))` to a string `"a b c d e"` – jcubic May 04 '21 at 07:09
  • @jcubic The question is "How to convert list to string in Emacs Lisp?" And I found your question trying to get an answer to mine. Alexander Gromnitsky answered my question and I adapted it. And if I found your question smb may also just need my answer for their same question "How to convert list to string in Emacs Lisp?" – Evgeny Mikhaylov May 04 '21 at 07:21