std::insert_iterator(3)

NAME
std::insert_iterator - std::insert_iterator

Synopsis
   Defined in header <iterator>
   template< class Container >
   class insert_iterator : public (until C++17)
   std::iterator<std::output_iterator_tag,
                        void, void, void, void>
   template< class Container > (since C++17)
   class insert_iterator;
   std::insert_iterator is a LegacyOutputIterator that inserts elements into a
   container for which it was constructed, at the position pointed to by the supplied
   iterator. The container's insert() member function is called whenever the iterator
   (whether dereferenced or not) is assigned to. Incrementing the std::insert_iterator
   is a no-op.

Member types
   Member type Definition
   iterator_category std::output_iterator_tag
   value_type void
   difference_type void (until C++20)
                     std::ptrdiff_t (since C++20)
   pointer void
   reference void
   container_type Container
   Member types iterator_category, value_type, difference_type, pointer
   and reference are required to be obtained by inheriting from (until C++17)
   std::iterator<std::output_iterator_tag, void, void, void, void>.

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

Member objects
   Member name Definition
   container (protected member object) a pointer of type Container*
                        an iterator of type
                        Container::iterator
   iter (protected member object) \fPfI(until C++20)
                        ranges::iterator_t<Container>
                        (since C++20)

Example
// Run this code
 #include <algorithm>
 #include <iostream>
 #include <iterator>
 #include <list>
 #include <vector>
 int main()
 {
     std::vector<int> v{1, 2, 3, 4, 5};
     std::list<int> l{-1, -2, -3};
     std::copy(v.begin(), v.end(), // may be simplified with std::inserter
               std::insert_iterator<std::list<int>>(l, std::next(l.begin())));
     for (int n : l)
         std::cout << n << ' ';
     std::cout << '\n';
 }

Output:
 -1 1 2 3 4 5 -2 -3

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