Strange behaviour of match-string/string-match

Question

I have this code

(defun string-match-test ()
  (interactive)
  (string-match "12345" (buffer-string))
  (setq STRING (match-string 0))
  (read-string STRING)
  (goto-char (point-max))
  (insert STRING)
  )

(string-match-test)

I expected it to print 12345 but I get, instead "1234. What's my mistake? May I have misunderstood the buffer-string function behaviour?

Note. I kwow I can use serch-forward-regexp combined with with-temp-buffer... but I'd like to understand the reason of this weird behaviur.

score 3 · Accepted Answer · answered Jul 14 '17 at 08:33

3

See the documentation of match-string. It contains:

(match-string NUM &optional STRING)
...
STRING should be given if the last search was by ‘string-match’ on STRING.

answered Jul 14 '17 at 08:33

Marco Wahl

2,796
11
13

Thank you. Actually I thought that the current buffer and the `buffer-string` output was the same thing/string. – Gabriele Nicolardi Jul 14 '17 at 08:44
Yeah! So much to discover and learn. Same here. ;) – Marco Wahl Jul 15 '17 at 11:24

Strange behaviour of match-string/string-match

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