errno_t memset_s(void *s, rsize_t smax, int c, rsize_t n);
memset_s copies the value of c (converted to an unsigned char) into each of the first n characters of the object pointed to by s whose size is supplied in s1max. The parameters are checked for null pointer cases. On error the current constraint_handler is called.
memset_s returns 0 on success and non-zero on failure.