I'd like to write something like this except to compare the region with a regexp.

(if (string-match (buffer-substring-no-properties (point) (mark))

Is there an equivalent of string-match for regexp that I can use like this

(if (regexp-match (buffer-substring-no-properties (point) (mark))

so that it returns true if the selected region is "Apple" and nil if it's "apple"?

  • 8
    A few random remarks : (i) string-match already uses regexps (ii) let-bind case-fold-search to nil around your call if you want case sensitivity (iii) use looking-at for matching text at point (iv) you can use region-beginning and region-end instead of point and mark in case the latter is before the former (bonus point for making sure use-region-p is non-nil) – YoungFrog Jan 18 '16 at 11:40
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    @YoungFrom I think item (i) qualifies as an answer. – T. Verron Jan 18 '16 at 12:40
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    C-h f string-match would tell you. – Jordon Biondo Jan 18 '16 at 16:51

For the sake of an answer:

string-match is meant for to be used with regexps.

(string-match REGEXP STRING &optional START)

Return index of start of first match for REGEXP in STRING, or nil. Matching ignores case if ‘case-fold-search’ is non-nil. If third arg START is non-nil, start search at that index in STRING. For index of first char beyond the match, do (match-end 0). ‘match-end’ and ‘match-beginning’ also give indices of substrings matched by parenthesis constructs in the pattern.

You can use the function ‘match-string’ to extract the substrings matched by the parenthesis constructions in REGEXP.

Here are some examples

(string-match "\\(dog\\|cat\\)" "There is a dog.") ;; => 11
(string-match "\\(dog\\|cat\\)" "There are two cats here." 0) ;; => 14
(string-match "\\(dog\\|cat\\)" "There are two cats here." 15) ;; => nil
(string-match "\\(dog\\|cat\\)" "There are horses.") ;; => nil

Note that if you don't plan on using match-data after using string-match you should prefer to use string-match-p which works just like string-match except that it doesn't modify match-data when run.

As other have said, in your case looking-at would probably be a better choice anyway.

(looking-at REGEXP)

Return t if text after point matches regular expression REGEXP. This function modifies the match data that ‘match-beginning’, ‘match-end’ and ‘match-data’ access; save and restore the match data if you want to preserve them.

  • Given that the OP got the argument order wrong, it would probably be a good idea to show an example snippet calling string-match. – Malabarba Feb 9 '16 at 18:42

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