std::unordered_map<Key,T,Hash,KeyEqual,Allocator>::insert_range

Inserts a copy of each element in the range rg if and only if there is no element with key equivalent to the key of that element in *this

Each iterator in the range rg is dereferenced exactly once. The behavior is undefined if rg

If after the operation the new number of elements is greater than old max_load_factor() * bucket_count() a rehashing takes place.

Parameters

Return value

(none)

Complexity

Average case O(N), where N is ranges::distance(rg) , worst case O( N·(a.size() + 1)

Notes

Example

#include <iostream>
#include <unordered_map>
#include <utility>
 
void println(auto, auto const& container)
{
    for (const auto& [key, value] : container)
        std::cout << '{' << key << ',' << value << '}' << ' ';
    std::cout << '\n';
}
 
int main()
{
    auto container = std::unordered_map{std::pair{1, 11}, {3, 33}, {2, 22}, {4, 44}};
    const auto rg = {std::pair{-1, -11}, {3, -33}, {-2, -22}};
#ifdef __cpp_lib_containers_ranges
    container.insert_range(rg);
#else
    container.insert(rg.begin(), rg.end());
#endif
    println("{}", container);
}

{4,44} {-1,-11} {2,22} {3,33} {-2,-22} {1,11}

See also