c-set-offset is an interactive autoloaded compiled Lisp function in `cc-styles.el'.

(c-set-offset SYMBOL OFFSET &optional IGNORED)

Change the value of a syntactic element symbol in `c-offsets-alist'.
SYMBOL is the syntactic element symbol to change and OFFSET is the new
offset for that syntactic element. The optional argument is not used
and exists only for compatibility reasons.