std::flat_set<Key,Compare,KeyContainer>::extract

 

C++

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Feature test macros (C++20)

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Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

inplace_vector (C++26)

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forward_list (C++11)

list

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set

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unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

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flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

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span (C++20)

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std::flat_set

Member types

Member functions

flat_set::flat_set flat_set::operator= Iterators flat_set::beginflat_set::cbegin flat_set::endflat_set::cend flat_set::rbeginflat_set::crbegin flat_set::rendflat_set::crend Capacity flat_set::size flat_set::max_size flat_set::empty Observers flat_set::key_comp flat_set::value_comp      Modifiers flat_set::clear flat_set::insert flat_set::insert_range flat_set::emplace flat_set::emplace_hint flat_set::erase flat_set::swap flat_set::extract flat_set::replace Lookup flat_set::count flat_set::find flat_set::contains flat_set::equal_range flat_set::lower_bound flat_set::upper_bound Non-member functions operator==operator<=> swap(std::flat_set) erase_if(std::flat_set)

Helper classes

uses_allocator<std::flat_set>

Tags

sorted_unique      sorted_unique_t

Deduction guides

 

container_type extract() &&;		(since C++23)

Extracts adapted container c. Equivalent to return std::move(c);.

After this operation *this is empty, even if an exception is thrown.

Parameters

(none)

Return value

std::move(c).

Complexity

Constant.

Example

Run this code

#include <cassert>
#include <flat_set>
#include <print>
#include <type_traits>
#include <vector>
 
int main()
{
    std::flat_set<int> set{1, 2, 3};
    const auto size = set.size();
 
    auto c = set.extract();
    assert(c.size() == size);
    assert(set.empty());
    assert(set.keys().empty());
    assert(set.values().empty());
 
    // The default keys container is std::vector:
    static_assert(std::is_same_v<decltype(c), std::vector<int>>);
 
    std::println("{}", c);
}

Output:

[1, 2, 3]

See also

replace

replaces the underlying container (public member function)