NAME¶

std::inserter - std::inserter

Synopsis¶

Defined in header <iterator>
template< class Container >
std::insert_iterator<Container> inserter( Container& c, typename (until C++20)
Container::iterator i );
template< class Container >
constexpr std::insert_iterator<Container> inserter( Container& c, (since C++20)
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 an 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 multi-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> v {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(v, std::next(v.begin())));

for (int n : v)
std::cout << n << ' ';
std::cout << '\n';
}

Output:¶

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

See also¶

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