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

 

C++

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Feature test macros (C++20)

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Filesystem library (C++17)

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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

multiset

map

multimap

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unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

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

 

template< class... Args > std::pair<iterator, bool> emplace( Args&&... args );		(since C++23)

Inserts a new element into the container constructed in-place with the given args, if there is no element with the key in the container.

First, initializes an object t of type value_type with std::forward<Args>(args)..., then inserts t as if by

auto it = ranges::upper_bound(c, t, compare);
c.insert(it, std::move(t));

This overload participates in overload resolution only if std::is_constructible_v<value_type, Args...> is true.

Careful use of emplace allows the new element to be constructed while avoiding unnecessary copy or move operations.

Parameters

args

-

arguments to forward to the constructor of the element

Return value

A pair consisting of an iterator to the inserted element (or to the element that prevented the insertion) and a bool value set to true if and only if the insertion took place.

Exceptions

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

Complexity

Logarithmic in the size of the container.

See also

emplace_hint	constructs elements in-place using a hint (public member function)
insert	inserts elements (public member function)