What are function objects in C++ STL?

Can you explain what function objects are in C++ STL?

Function objects, or functors, are objects that can be called as if they were functions. They are used in STL algorithms.

How do I create a function object in C++?

You can create a function object by defining a class with an overloaded operator(). This allows instances of the class to be called like functions.

Can you give me an example of a function object?

Sure! Here's a simple example:

struct Add {
    int operator()(int a, int b) {
        return a + b;
    }
};

You can then use it like this:

Add add;
int result = add(2, 3); // result will be 5

What are the advantages of using function objects?

Function objects can maintain state, are more flexible than regular functions, and can be used with STL algorithms for better performance.