I want to replace a character inside a word, so I wrote:

(setq regexp "[ab]")
(and (re-search-backward regexp nil t 1)
     (replace-match "c"))

This replaces a or b to c as I wish, but I want to set a bound of it. There is a BOUND option with re-search-backward. How can I make the match only a word that is under the current cursor?

Thanks for @jackson I can write the function, but still it doesn't work properly.

(setq regexp ".*[ab].*")
(defun test-it ()
      (narrow-to-region (progn (backward-word) (point))
                        (progn (forward-word) (point)))
      (and (re-search-backward regexp)
           (replace-match "c")))))

Thins function replaces ab to ac and ad to cd as I expected, but it doesn't replace ac to cc. Why?

  • Out of curiosity, are you implement some sort of auto-correction here? Nov 12, 2015 at 19:21
  • I want make a pinyin (Chinese tone mark) input mode. like ma -> mǎ. So I want to replace aāáà to ǎ by a function. I can write it separatey by using ("a" "ǎ") ("ā" "ǎ") ("á" "ǎ") ("à" "ǎ"). But I thought it is a bit redundant.
    – ironsand
    Nov 12, 2015 at 19:35
  • Yay, finally a chinese introduction lesson I took years ago helps me tell that this has something to do with mother and horse :) I don't understand or type in Chinese, but have you looked at set-input-method and toggle-input-method? Nov 12, 2015 at 20:01
  • Also, is this for an occcasional phonetics correction? If not, you can probably modify the solution here for fixing double caps to always "autocorrect" based on custom rules like ma* to , ma- to , ma` to , and so on. Nov 12, 2015 at 20:05
  • As far as I know these two method are intended someone who can type Chinese, right? I want to make a minor mode for the phonetics notation.
    – ironsand
    Nov 12, 2015 at 20:08

1 Answer 1


Not quite sure what you're asking. If you're using re-search-backward because you want to include the beginning of the word that encompasses the point, perhaps this does what you want:

(setq regexp ".*[ab].*")
(defun test-it ()
      (narrow-to-region (progn (backward-word 1) (point))
                        (progn (forward-word 1) (point)))
      (backward-word 1)
      (if (looking-at regexp)
          (replace-match "frog")))))

The code is a bit clumsy, but will replace the regexp with the given string if it matches.

  • Thanks for your help! I changed your code a little because I want to search the string backward from the (point). But my code have still a problem, it would be very nice if you can take a glance at it.
    – ironsand
    Nov 12, 2015 at 20:17
  • 1
    I changed the regexp to be .*[ab].* - you probably don't want the .* - I did because I was checking to see if the entire word would be replaced. You're just replacing a single character. Nov 12, 2015 at 20:45

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