c-guess-region-no-install is an interactive autoloaded compiled Lisp function in `cc-guess.el'.

(c-guess-region-no-install START END &optional ACCUMULATE)

Guess the style on the region; don't install it.

Every line of code in the region is examined and values for the following two
variables are guessed:

* `c-basic-offset', and
* the indentation values of the various syntactic symbols in

The guessed values are put into `c-guess-guessed-basic-offset' and

Frequencies of use are taken into account when guessing, so minor
inconsistencies in the indentation style shouldn't produce wrong guesses.

If given a prefix argument (or if the optional argument ACCUMULATE is
non-nil) then the previous examination is extended, otherwise a new
guess is made from scratch.

Note that the larger the region to guess in, the slower the guessing.
So you can limit the region with `c-guess-region-max'.