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

template< container-compatible-range<value_type> R > void insert_range( R&& rg );		(since C++23)

Inserts a copy of each element of 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 overlaps with the container.

Parameters

rg	-	a container compatible range, that is, an `input_range` whose elements are convertible to `T`.
Type requirements
- `value_type` must be EmplaceConstructible into `unordered_map` from *ranges::begin(rg). Otherwise, the behavior is undefined.

Return value

(none)

Complexity

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

Notes

Feature-test macro	Value	Std	Comment
`__cpp_lib_containers_ranges`	202202L	(C++23)	Ranges-aware construction and insertion

Example

Run this code

#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);
}

Possible output:

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

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unordered_map::unordered_map
unordered_map::~unordered_map
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unordered_map::beginunordered_map::cbegin
unordered_map::endunordered_map::cend
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unordered_map::empty
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unordered_map::clear
unordered_map::insert
unordered_map::insert_range (C++23)
unordered_map::insert_or_assign (C++17)
unordered_map::emplace
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operator==operator!= (until C++20)
std::swap
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