Question

Which of the following is correct about Functors?

(a) Functors should not be declared outside the main function

(b) Overloaded operator () function is not a member of the class

(c) Functors should be declared global

(d) Functors have a state

I have been asked this question in unit test.

This key question is from Functors in section Algorithms, Objects & Iterators in C++ of C++

Answer 1

The correct choice is (d) Functors have a state

The explanation is: Functors are objects of a class which also have other members and member functions which can be used to save states of that functors hence functors have a state. Functors can be declared anywhere in a program.