Standard library header <deque>

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Standard library headers

Language support <cfloat> <climits> <compare> (C++20) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) Concepts <concepts> (C++20) Diagnostics <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) Memory management <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) Metaprogramming <type_traits> (C++11) <ratio> (C++11)

General utilities <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) Containers <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> Iterators <iterator> Ranges <generator> (C++23) <ranges> (C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> Text processing <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    Numerics <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <valarray> Time <chrono> (C++11) <ctime> C compatibility <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

Input/output <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) Concurrency support <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) Execution support <execution> (C++17)

 

This header is part of the containers library.

Includes
<compare> (C++20)	Three-way comparison operator support
<initializer_list> (C++11)	std::initializer_list class template
Classes
deque	double-ended queue (class template)
Functions
operator==operator!=operator<operator<=operator>operator>=operator<=> (removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20)	lexicographically compares the values of two deques (function template)
std::swap(std::deque)	specializes the std::swap algorithm (function template)
erase(std::deque)erase_if(std::deque) (C++20)	erases all elements satisfying specific criteria (function template)
Range access
begincbegin (C++11)(C++14)	returns an iterator to the beginning of a container or array (function template)
endcend (C++11)(C++14)	returns an iterator to the end of a container or array (function template)
rbegincrbegin (C++14)	returns a reverse iterator to the beginning of a container or array (function template)
rendcrend (C++14)	returns a reverse end iterator for a container or array (function template)
sizessize (C++17)(C++20)	returns the size of a container or array (function template)
empty (C++17)	checks whether the container is empty (function template)
data (C++17)	obtains the pointer to the underlying array (function template)

Synopsis

#include <compare>
#include <initializer_list>
 
namespace std {
  // class template deque
  template<class T, class Allocator = allocator<T>>
  class deque;
 
  template<class T, class Allocator>
  bool operator==(const deque<T, Allocator>& x, const deque<T, Allocator>& y);
  template<class T, class Allocator>
  /*synth-three-way-result*/<T> operator<=>(const deque<T, Allocator>& x,
                                            const deque<T, Allocator>& y);
 
  template<class T, class Allocator>
  void swap(deque<T, Allocator>& x, deque<T, Allocator>& y) noexcept(noexcept(x.swap(y)));
 
  // erasure
  template<class T, class Allocator, class U = T>
  typename deque<T, Allocator>::size_type erase(deque<T, Allocator>& c, const U& value);
  template<class T, class Allocator, class Predicate>
  typename deque<T, Allocator>::size_type erase_if(deque<T, Allocator>& c,
                                                   Predicate pred);
 
  namespace pmr {
    template<class T>
    using deque = std::deque<T, polymorphic_allocator<T>>;
  }
}

Class template std::deque

namespace std {
  template<class T, class Allocator = allocator<T>>
  class deque
  {
  public:
    // types
    using value_type             = T;
    using allocator_type         = Allocator;
    using pointer                = typename allocator_traits<Allocator>::pointer;
    using const_pointer          = typename allocator_traits<Allocator>::const_pointer;
    using reference              = value_type&;
    using const_reference        = const value_type&;
    using size_type              = /* implementation-defined */;
    using difference_type        = /* implementation-defined */;
    using iterator               = /* implementation-defined */;
    using const_iterator         = /* implementation-defined */;
    using reverse_iterator       = std::reverse_iterator<iterator>;
    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
 
    // construct/copy/destroy
    deque()
      : deque(Allocator())
    {
    }
    explicit deque(const Allocator&);
    explicit deque(size_type n, const Allocator& = Allocator());
    deque(size_type n, const T& value, const Allocator& = Allocator());
    template<class InputIter>
    deque(InputIter first, InputIter last, const Allocator& = Allocator());
    template<container-compatible-range<T> R>
    deque(from_range_t, R&& rg, const Allocator& = Allocator());
    deque(const deque& x);
    deque(deque&&);
    deque(const deque&, const type_identity_t<Allocator>&);
    deque(deque&&, const type_identity_t<Allocator>&);
    deque(initializer_list<T>, const Allocator& = Allocator());
 
    ~deque();
    deque& operator=(const deque& x);
    deque& operator=(deque&& x) noexcept(
      allocator_traits<Allocator>::is_always_equal::value);
    deque& operator=(initializer_list<T>);
    template<class InputIter>
    void assign(InputIter first, InputIter last);
    template<container-compatible-range<T> R>
    void assign_range(R&& rg);
    void assign(size_type n, const T& t);
    void assign(initializer_list<T>);
    allocator_type get_allocator() const noexcept;
 
    // iterators
    iterator begin() noexcept;
    const_iterator begin() const noexcept;
    iterator end() noexcept;
    const_iterator end() const noexcept;
    reverse_iterator rbegin() noexcept;
    const_reverse_iterator rbegin() const noexcept;
    reverse_iterator rend() noexcept;
    const_reverse_iterator rend() const noexcept;
 
    const_iterator cbegin() const noexcept;
    const_iterator cend() const noexcept;
    const_reverse_iterator crbegin() const noexcept;
    const_reverse_iterator crend() const noexcept;
 
    // capacity
    bool empty() const noexcept;
    size_type size() const noexcept;
    size_type max_size() const noexcept;
    void resize(size_type sz);
    void resize(size_type sz, const T& c);
    void shrink_to_fit();
 
    // element access
    reference operator[](size_type n);
    const_reference operator[](size_type n) const;
    reference at(size_type n);
    const_reference at(size_type n) const;
    reference front();
    const_reference front() const;
    reference back();
    const_reference back() const;
 
    // modifiers
    template<class... Args>
    reference emplace_front(Args&&... args);
    template<class... Args>
    reference emplace_back(Args&&... args);
    template<class... Args>
    iterator emplace(const_iterator position, Args&&... args);
 
    void push_front(const T& x);
    void push_front(T&& x);
    template<container-compatible-range<T> R>
    void prepend_range(R&& rg);
    void push_back(const T& x);
    void push_back(T&& x);
    template<container-compatible-range<T> R>
    void append_range(R&& rg);
 
    iterator insert(const_iterator position, const T& x);
    iterator insert(const_iterator position, T&& x);
    iterator insert(const_iterator position, size_type n, const T& x);
    template<class InputIter>
    iterator insert(const_iterator position, InputIter first, InputIter last);
    template<container-compatible-range<T> R>
    iterator insert_range(const_iterator position, R&& rg);
    iterator insert(const_iterator position, initializer_list<T>);
 
    void pop_front();
    void pop_back();
 
    iterator erase(const_iterator position);
    iterator erase(const_iterator first, const_iterator last);
    void swap(deque&) noexcept(allocator_traits<Allocator>::is_always_equal::value);
    void clear() noexcept;
  };
 
  template<class InputIter, class Allocator = allocator</*iter-value-type*/<InputIter>>>
  deque(InputIter, InputIter, Allocator = Allocator())
    -> deque</*iter-value-type*/<InputIter>, Allocator>;
 
  template<ranges::input_range R, class Allocator = allocator<ranges::range_value_t<R>>>
  deque(from_range_t, R&&, Allocator = Allocator())
    -> deque<ranges::range_value_t<R>, Allocator>;
}