std::front_inserter
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header  
<iterator>
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|   template< class Container > 
std::front_insert_iterator<Container> front_inserter( Container& c);  | 
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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.
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[edit] Parameters
| c | - |   container that supports a push_front operation
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[edit] Return value
A std::front_insert_iterator which can be used to add elements to the beginning of the container c
[edit] Possible implementation
template< class Container > std::front_insert_iterator<Container> front_inserter( Container& c) { return std::front_insert_iterator<Container>(c); }  | 
[edit] 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
[edit] See also
|    iterator adaptor for insertion at the front of a container   (class template)  | 
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|    creates a std::back_insert_iterator of type inferred from the argument  (function template)  | 
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|    creates a std::insert_iterator of type inferred from the argument  (function template)  | 
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