Is there an equivalent of string-match for regexp?

Question

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))
                  "foo")
    (bar))

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

(if (regexp-match (buffer-substring-no-properties (point) (mark))
                  "^[A-Z]")
    (bar))

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

Answer 1

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.