std::back_insert_iterator

 

C++

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Technical Specifications

 

Iterator library

Iterator primitives
iterator_traits
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag
iterator
Iterator adaptors
reverse_iterator move_iterator (C++11) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) back_inserter front_inserter inserter
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Container access
size (C++17)
empty (C++17)
data (C++17)

 

std::back_insert_iterator

Member functions

back_insert_iterator::back_insert_iterator

back_insert_iterator::operator=

back_insert_iterator::operator*

back_insert_iterator::operator++back_insert_iterator::operator++(int)

 

Defined in header <iterator>
template< class Container > class back_insert_iterator : public std::iterator< std::output_iterator_tag,                                                    void, void, void, void >		(until C++17)
template< class Container > class back_insert_iterator;		(since C++17)

std::back_insert_iterator is an OutputIterator that appends to a container for which it was constructed. The container's push_back() member function is called whenever the iterator (whether dereferenced or not) is assigned to. Incrementing the std::back_insert_iterator is a no-op.

Member types

Member type	Definition
container_type	Container

Member functions

(constructor)	constructs a new back_insert_iterator (public member function)
operator=	inserts an object into the associated container (public member function)
operator*	no-op (public member function)
operator++operator++(int)	no-op (public member function)

Member objects

Member name	Definition
container (protected)	a pointer of type Container*

Member types

Member type	Definition
value_type	void
difference_type	void
pointer	void
reference	void
iterator_category	std::output_iterator_tag

Note: before C++17, these member types are required to be obtained by inheriting from std::iterator<std::output_iterator_tag,void,void,void,void>.

Example

Run this code

#include <iostream>
#include <iterator>
#include <algorithm>
#include <cstdlib>
#include <vector>
 
int main()
{
    std::vector<int> v;
    std::generate_n(std::back_insert_iterator<std::vector<int>>(v), // can be simplified
                    10, [](){ return std::rand() % 10; });        // with std::back_inserter
    for (int n : v)
        std::cout << n << ' ';
    std::cout << '\n';
}

Output:

3 6 7 5 3 5 6 2 9 1

See also

back_inserter	creates a std::back_insert_iterator of type inferred from the argument (function template)
front_insert_iterator	iterator adaptor for insertion at the front of a container (class template)
insert_iterator	iterator adaptor for insertion into a container (class template)