I wonder if the book, which I assume is talking about Java, is ignoring the implicit zeroth argument which is the object you're invoking the function on. Obviously in C you have to make that parameter explicit, but I've got enough experience of both languages to know that people often don't consider the object to be a parameter to one of its member functions.

So if you're converting that rule back to C, you'd need to add one to each element of the rule. The one parameter rule is saying that when special cases are common, a special function to handle it is a good thing. So writing `i++` rather than `i = i + 1` or `next(node)` rather than `skip(node,1)`.