What's the difference between these ranged loops?

[Satan]

What's the difference between these ranged for loops and when is one used over the other and potential advantages?

   std::vector<int> v = {0, 1, 2, 3, 4, 5};
 
    for (const int& i : v) // access by const reference
        std::cout << i << ' ';
 
    for (auto i : v) // access by value, the type of i is int
        std::cout << i << ' ';
 
    for (auto&& i : v) // access by forwarding reference, the type of i is int&
        std::cout << i << ' ';
 
    const auto& cv = v;
 
    for (auto&& i : cv) // access by f-d reference, the type of i is const int&
        std::cout << i << ' ';
 

[Repeater]

This post covers them, and more, and explains when to use each: https://blog.petrzemek.net/2016/08/17/auto-type-deduction-in-range-based-for-loops/

[Satan]

Thanks a lot repeater!