Non-interactive emacs regex substitute

Question

Is there a (non-interactive) function in emacs lisp that replaces a matched regex in an arbitrary string?

i.e.

(sub regex search-string replace-string)

as in

(sub "[^.x/]" "beef./xxfoo" "")
;; => "./xx"

Answer 1

Yes, see function replace-regexp-in-string. Simple as that.

And to replace matching text in a buffer, you have replace-regexp.

The replacement does not need to be a literal string, but can involve retrieving parts of the regexp match and other manipulations. Use C-h f to see the doc for these functions.