C++ back_inserter

#include 
#include 
#include 
#include 

// g++ 4.9.2 x86_64
// g++ *.cpp -std=c++11

int main()
{
        std::vector<int> vec;
        auto it = std::back_inserter(vec); // assigning through it adds elements to vec
        *it = 42; // vec now has one element with value 42
        for (const auto &e : vec) {
                std::cout << e << " ";
        }
        std::cout << std::endl;

        std::vector<int> vec2;
        std::fill_n(std::back_inserter(vec2), 10, 0); // appends ten elements to vec2
        for (const auto &e : vec2) {
                std::cout << e << " ";
        }
        std::cout << std::endl;

        return 0;
}

From C++ Primer (5th) (Section 10.2.2)
back_inserter: Iterator adaptor that takes a reference to a container and
generates an insert iterator that uses push_back to add elements to the
specified container.