Std::inserter (3) Linux Manual Page

std::inserter – std::inserter

Synopsis

Defined in header <iterator>

template< class Container >                                                                           (until C++20)

std::insert_iterator<Container> inserter( Container& c, typename Container::iterator i );

template< class Container >                                                                           (since C++20)

constexpr std::insert_iterator<Container> inserter( Container& c, ranges::iterator_t<Container> i );

inserter is a convenience function template that constructs a std::insert_iterator for the container c and its iterator i with the type deduced from the type of the argument.

Parameters

c – container that supports a insert operation
i – iterator in c indicating the insertion position

Return value

A std::insert_iterator which can be used to insert elements into the container c at the position indicated by i.

Possible implementation

  template< class Container >
  std::insert_iterator<Container> inserter( Container& c, typename Container::iterator i )
  {
      return std::insert_iterator<Container>(c, i);
  }

Example

// Run this code

#include <algorithm>

#include <iostream>

#include <iterator>

#include <vector>

#include <set>
int main()

{
    std::multiset<int> s{1, 2, 3};
    // std::inserter is commonly used with sets
    std::fill_n(std::inserter(s, s.end()), 5, 2);
    for (int n : s)
        std::cout << n << ' ';
    std::cout << '\n';
    std::vector<int> d{100, 200, 300};
    std::vector<int> l{1, 2, 3, 4, 5};
    // when inserting in a sequence container, insertion point advances
    // because each std::insert_iterator::operator= updates the target iterator
    std::copy(d.begin(), d.end(), std::inserter(l, std::next(l.begin())));
    for (int n : l)
        std::cout << n << ' ';
    std::cout << '\n';
}

Output:

1 2 2 2 2 2 2 3
1 100 200 300 2 3 4 5

std::inserter (3) Linux Manual Page