#include <iostream>
#include <functional>

int add(int a, int b) {
    return a + b;
}

struct Multiply {
    int operator()(int a, int b) {
        return a * b;
    }
};

int main() {
    // Store a regular function
    std::function<int(int, int)> f1 = add;
    std::cout << "Result of add(5, 3): " << f1(5, 3) << std::endl;

    //R(Args...)
    //std::function< R(Args...) > f1a = add;


    // Store a lambda expression
    std::function<int(int, int)> f2 = [](int a, int b) { return a - b; };
    std::cout << "Result of lambda (-5, 3): " << f2(-5, 3) << std::endl;

    // Store a function object
    Multiply multiplier;
    std::function<int(int, int)> f3 = multiplier;
    std::cout << "Result of Multiply(7, 4): " << f3(7, 4) << std::endl;

    //Store a function pointer
    int(*func_ptr)(int, int) = add;
    std::function<int(int, int)> f4 = func_ptr;
    std::cout << "Result of func_ptr(10, 2): " << f4(10, 2) << std::endl;

    return 0;
}