Using lambda as callback

#include <iostream>
#include <vector>
#include <functional>

//mix old C code just for concept proof
#include <stdio.h>

using namespace std;

//class with callbacks
class WorkingClass
{
public:
	typedef const std::function<void(int)> handler_t;
	
	void AddHandler(handler_t& h)
	{
		handlerList.push_back(&h);
	}
	
	void DoStuff()
	{
		for(auto& handler: handlerList)
		{
			(*handler)(42);
			(*handler)(23);
		}
	}
	
private:
	std::vector<handler_t*> handlerList;
	
};

//using legacy coe
void do_something( void(*callback)(void*), void* callback_arg)
{
	callback(callback_arg);
}

//tradicional functor in c++ (overload operator() )
//used for: e.g.:function with state
struct AddF
{
	AddF(int x): x(x) {}
	int operator()(int y) const { return x + y; }
private:
	int x; 
};


/* tradicional functors in Plain C */
void fun(int a)
{
	printf("value %d", a);
}

int main()
{
	/* Exercise 01 */
	WorkingClass wc;
	wc.AddHandler([&](int num){ cout << "A: " << num << endl; } );
	wc.AddHandler([&](int num){ cout << "B: " << num << endl; } );
	wc.DoStuff();			  
	
	/* Exercise 02 */
	int num_callbacks = 0;
	auto callback =[&](){
		std::cout << "callback called " << ++num_callbacks << " times \n";
	};
	
	auto thunk = [](void* arg){
		(*static_cast<decltype(callback)*>(arg))();
	};
	
	do_something(thunk, &callback);
	
	/* Exercise 03 */
	auto lambda = [](int a, float b) {
		std::cout << "a: " << a << std::endl;
		std::cout << "b: " << b << std::endl;
	};
	//function being a raw pointer
	auto function = static_cast<void(*)(int, float)>(lambda);
	function(1, 2.13);
	//function begin a std::function
	auto function2 = static_cast<std::function<void(int, float)>>(lambda);
	function2(1, 2.13);


	
	// C++ tradicional functors
	AddF ff(3);
	int fff = ff(7);
	std::cout  << fff << std::endl;


	
	// C tradiciona function pointer	
	// return type( *name of var )(args01,args02, ...)	
	void(*fun_ptr)(int) = &fun;
	/* The above line is equivalent of following two 
	void (*fun_ptr)(int); 
	fun_ptr = &fun;*/
	(*fun_ptr)(10); // de-referencing a function pointer and add variables
	
	return 0;
}