Use the following iterator adapters to insert new elements in a container:

• std::back_inserter() to insert elements at the end, for containers that have a push_back() method:

        std::vector<int> v{ 1,2,3,4,5 };
        std::fill_n(std::back_inserter(v), 3, 0);
        // v={1,2,3,4,5,0,0,0}

• std::front_inserter() to insert elements at the beginning, for containers that have a push_front() method:

        std::list<int> l{ 1,2,3,4,5 };
        std::fill_n(std::front_inserter(l), 3, 0);
        // l={0,0,0,1,2,3,4,5}

• std::inserter() to insert anywhere in a container, for containers that have an insert() method:

        std::vector<int> v{ 1,2,3,4,5 };
        std::fill_n(std::inserter(v, v.begin()), 3, 0);
        // v={0,0,0,1,2,3,4,5}

        std::list<int> l{ 1,2,3,4,5 };
        auto it = l.begin();
        std::advance(it, 3);
        std::fill_n(std::inserter(l, it), 3, 0);
        // l={1,2,3,0,0,0,4,5}