Question

You can check to see whether an R object is NULL with the _________ function.

(a) is.null()

(b) is.nullobj()

(c) null()

(d) as.nullobj()

I got this question in homework.

The origin of the question is Functions topic in portion Control Structures, Functions, Scoping Rules, Loop Functions and Debugging of R Programming

Answer 1

Right answer is (a) is.null()

To elaborate: It is sometimes useful to allow an argument to take the NULL value, which might indicate that the function should take some specific action.