Adaptors

Iterator adaptors enable the use of iterators in insert mode or with streams. They need the header <iterator>.

Insert iterators

With the three insert iterators std::front_inserter, std::back_inserter, and std::inserter, we can insert an element into a container at the beginning, at the end or an arbitrary position respectively. The memory for the elements will be automatically provided. All of these insert iterators map their functionality on the underlying methods of the container cont.

The table below gives us two pieces of information: Which methods of the containers are internally used and which iterators can be used depending on the container’s type.

Name	Internally-used Method	Container
std::front_inserter(val)	cont.push_front(val)	std::deque
		std::list
std::back_inserter(val)	cont.push_back(val)	std::vector
		std::deque
		std::list
		std::string
std::inserter(val, pos)	cont.insert(pos, val)	std::vector
		std::deque
		std::list
		std::string
		std::map
		std::set

The three insert iterators

We can combine the algorithms in the STL with the three insert iterators.