Reversing the order of letters/characters of a selected region

Question

How can one reverse the letters/characters in a selected region?

xyz --> zyx

ab cde --> edc ba

score 13 · Accepted Answer · answered Jan 17 '18 at 16:16

13

Emacs doesn't seem to provide any function to do this out of the box, but implementing one isn't that hard:

(defun my-reverse-region (beg end)
 "Reverse characters between BEG and END."
 (interactive "r")
 (let ((region (buffer-substring beg end)))
   (delete-region beg end)
   (insert (nreverse region))))

answered Jan 17 '18 at 16:16

1

Perfect, works well. – Name Jan 17 '18 at 16:23
2

Mark my answer as an solution if it helped you. – Jan 17 '18 at 16:38
Of course. Usually I wait for a while for alternative solutions, then mark it as accepted. – Name Jan 17 '18 at 16:43
4

You can also use delete-and-extract-region, i.e., (insert (nreverse (delete-and-extract-region beg end))). – xuchunyang Jan 17 '18 at 19:32
How do you use it with Meta + x? If I highlight a region (e.g. the abc string) and then execute it, I get the following error: Wrong type argument: listp, #("abc" 0 3 (fontified t)) – user3019105 Sep 14 '19 at 20:47
@tonix can you try with emacs -q? – Sep 15 '19 at 09:03
@DoMiNeLa10 Should I run it in terminal when starting emacs? – user3019105 Sep 15 '19 at 10:07

score 1 · Answer 2 · edited Jun 27 '22 at 18:52

1

Since emacs can call the shell on a region of text, and since shell can reverse text I believe there's an alternative/elegant(?) solution to the OPs problem,.

That's a comment but not an answer

okay how about

    ;; select the region, then
    C-u M-|
    ;; Shell command on region:
    rev<enter>

edited Jun 27 '22 at 18:52

NickD

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answered Jun 27 '22 at 16:07

american-ninja-warrior

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... although it reverses lines, not the region. – NickD Jun 27 '22 at 19:03

Reversing the order of letters/characters of a selected region

2 Answers2