What are some examples of functors in C++?

Can you explain what a functor is in C++?

Sure! A functor in C++ is an object that can be called as if it were a function. It is typically implemented by overloading the operator().

Can you give me an example of a functor?

Absolutely! Here's a simple example:

class Adder {
public:
    Adder(int x) : x_(x) {}
    int operator()(int y) const { return x_ + y; }
private:
    int x_;
};

In this example, Adder is a functor that adds a fixed value to its input.

How do I use this functor in my code?

You can use the functor like this:

Adder add5(5);
int result = add5(10); // result will be 15

Are there any advantages to using functors over regular functions?

Yes! Functors can maintain state, can be passed around like objects, and can be more flexible than regular functions.