c-beginning-of-statement is an interactive compiled Lisp function in `cc-cmds.el'.

(c-beginning-of-statement &optional COUNT LIM SENTENCE-FLAG)

Go to the beginning of the innermost C statement.
With prefix arg, go back N - 1 statements. If already at the
beginning of a statement then go to the beginning of the closest
preceding one, moving into nested blocks if necessary (use
C-M-b to skip over a block). If within or next to a
comment or multiline string, move by sentences instead of statements.

When called from a program, this function takes 3 optional args: the
repetition count, a buffer position limit which is the farthest back
to search for the syntactic context, and a flag saying whether to do
sentence motion in or near comments and multiline strings.

Note that for use in programs, `c-beginning-of-statement-1' is
usually better. It has much better defined semantics than this one,
which is intended for interactive use, and might therefore change to
be more "DWIM:ey".