std::front_inserter

From cppreference.com
< cpplrm; | iterator
Defined in header <iterator>
template< class Container >
std::front_insert_iterator<Container> front_inserter( Container& c );

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

Parameters

c - container that supports a push_front operation

Return value

A std::front_insert_iterator which can be used to add elements to the beginning of the container c

Possible implementation

template< class Container >
std::front_insert_iterator<Container> front_inserter( Container& c )
{
    return std::front_insert_iterator<Container>(c);
}

Example

#include <iostream>
#include <deque>
#include <algorithm>
#include <iterator>

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

Output:

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

See also

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