What is the difference between functors and functions?

Can you explain the difference between functors and functions?

Sure! In programming, a function is a block of code that performs a specific task, while a functor is an object that can be treated like a function. Functors can hold state and can be invoked like functions.

Can you give me an example of a functor?

Absolutely! In C++, a functor is typically a class or struct that overloads the operator(). For example:

class Adder {
public:
    int operator()(int a, int b) {
        return a + b;
    }
};

Here, Adder can be used like a function to add two numbers.

How do functors differ from regular functions in terms of usage?

Functors can maintain state between calls, while regular functions cannot. This allows functors to be more flexible in certain contexts, such as when you need to pass additional data or configuration.

Are there any performance differences between using functors and functions?

Yes, there can be performance differences. Functors may introduce some overhead due to object creation, but they can also be optimized by the compiler. In many cases, the performance difference is negligible.