C++11 function

#include <iostream>
#include <functional>
#include <vector>
using namespace std;

// c type global function
int c_func(int a, int b)
{
    return a + b;
}

//function object
class functor
{
public:
    int operator() (int a, int b)
    {
        return a + b;
    }
};

int main()
{
    //old use way
    typedef int (*F)(int, int);
    F f = c_func;
    cout<<f(1,2)<<endl;

    functor ft;
    cout<<ft(1,2)<<endl;

    /////////////////////////////////////////////

    std::function< int (int, int) > myfunc;

    myfunc = c_func;
    cout<<myfunc(3,4)<<endl;

    myfunc = ft;
    cout<<myfunc(3,4)<<endl;

    //lambda
    myfunc = [](int a, int b) { return a + b;};
    cout<<myfunc(3, 4)<<endl;

    //////////////////////////////////////////////

    std::vector<std::function<int (int, int)> > v;
    v.push_back(c_func);
    v.push_back(ft);
    v.push_back([](int a, int b) { return a + b;});

    for (const auto& e : v)
    {
        cout<<e(10, 10)<<endl;
    }

    return 0;
}