# std::back_inserter

From cppreference.com
< cpp‎ | iterator

Defined in header `<iterator>` |  |
template< class Container > std::back_insert_iterator<Container> back_inserter( Container& c ); |  | (until C++20)
template< class Container > constexpr std::back_insert_iterator<Container> back_inserter( Container& c ); |  | (since C++20)

`back_inserter` is a convenience function template that constructs a std::back_insert_iterator for the container `c` with the type deduced from the type of the argument.

### Parameters

c | - | container that supports a push_back operation

### Return value

A std::back_insert_iterator which can be used to add elements to the end of the container `c`

### Possible implementation

    template< class Container >
    std::back_insert_iterator<Container> back_inserter( Container& c )
    {
        return std::back_insert_iterator<Container>(c);
    }

### Example

Run this code

    #include <iostream>
    #include <vector>
    #include <algorithm>
    #include <iterator>

    int main()
    {
        std::vector<int> v{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
        std::fill_n(std::back_inserter(v), 3, -1);
        for (int n : v)
            std::cout << n << ' ';
    }

Output:

    1 2 3 4 5 6 7 8 9 10 -1 -1 -1

### See also

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

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/iterator/back_inserter&oldid=107590"