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Standard library header <vector>

This header is part of the containers library.

Includes
(C++20)
 Three-way comparison operator support
(C++11)
 std::initializer_list class template

Classes
dynamic contiguous array
(class template)
space-efficient dynamic bitset
(class template specialization)
(C++11)
 hash support for std::vector<bool>
(class template specialization)
Forward declarations
Defined in header <functional>
(C++11)
 hash function object
(class template)

Functions
(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 in the vector
(function template)
specializes the std::swap algorithm
(function template)
(C++20)
 erases all elements satisfying specific criteria
(function template)
Range access
(C++11)(C++14)
 returns an iterator to the beginning of a container or array
(function template)
(C++11)(C++14)
 returns an iterator to the end of a container or array
(function template)
(C++14)
 returns a reverse iterator to the beginning of a container or array
(function template)
(C++14)
 returns a reverse end iterator for a container or array
(function template)
(C++17)(C++20)
 returns the size of a container or array
(function template)
(C++17)
 checks whether the container is empty
(function template)
(C++17)
 obtains the pointer to the underlying array
(function template)

Synopsis

#include <compare>
#include <initializer_list>
 
namespace std {
  // class template vector
  template<class T, class Allocator = allocator<T>> class vector;
 
  template<class T, class Allocator>
    constexpr bool operator==(const vector<T, Allocator>& x,
                              const vector<T, Allocator>& y);
  template<class T, class Allocator>
    constexpr __synth_three_way_result<T> operator<=>(const vector<T, Allocator>& x,
                                                    const vector<T, Allocator>& y);
 
  template<class T, class Allocator>
    constexpr void swap(vector<T, Allocator>& x, vector<T, Allocator>& y)
      noexcept(noexcept(x.swap(y)));
 
  // erasure
  template<class T, class Allocator, class U>
    constexpr typename vector<T, Allocator>::size_type
      erase(vector<T, Allocator>& c, const U& value);
  template<class T, class Allocator, class Predicate>
    constexpr typename vector<T, Allocator>::size_type
      erase_if(vector<T, Allocator>& c, Predicate pred);
 
  namespace pmr {
    template<class T>
      using vector = std::vector<T, polymorphic_allocator<T>>;
  }
 
  // specialization of vector for bool
  // partial class template specialization vector<bool, Allocator>
  template<class Allocator>
    class vector<bool, Allocator>;
 
  template<class T>
    constexpr bool __is_vector_bool_reference = /* see description */; // exposition only
 
  // hash support
  template<class T> struct hash;
  template<class Allocator> struct hash<vector<bool, Allocator>>;
 
  // formatter specialization for vector<bool>
  template<class T, class CharT> requires __is_vector_bool_reference<T>
    struct formatter<T, CharT>;
}

Class template std::vector 

namespace std {
  template<class T, class Allocator = allocator<T>>
  class vector {
  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
    constexpr vector() noexcept(noexcept(Allocator())) : vector(Allocator()) { }
    constexpr explicit vector(const Allocator&) noexcept;
    constexpr explicit vector(size_type n, const Allocator& = Allocator());
    constexpr vector(size_type n, const T& value, const Allocator& = Allocator());
    template<class InputIt>
      constexpr vector(InputIt first, InputIt last, const Allocator& = Allocator());
    template<__container_compatible_range<T> R>
      constexpr vector(from_range_t, R&& rg, const Allocator& = Allocator());
    constexpr vector(const vector& x);
    constexpr vector(vector&&) noexcept;
    constexpr vector(const vector&, const type_identity_t<Allocator>&);
    constexpr vector(vector&&, const type_identity_t<Allocator>&);
    constexpr vector(initializer_list<T>, const Allocator& = Allocator());
    constexpr ~vector();
    constexpr vector& operator=(const vector& x);
    constexpr vector& operator=(vector&& x)
      noexcept(
        allocator_traits<Allocator>::propagate_on_container_move_assignment::value ||
        allocator_traits<Allocator>::is_always_equal::value
      );
    constexpr vector& operator=(initializer_list<T>);
    template<class InputIt>
      constexpr void assign(InputIt first, InputIt last);
    template<__container_compatible_range<T> R>
      constexpr void assign_range(R&& rg);
    constexpr void assign(size_type n, const T& u);
    constexpr void assign(initializer_list<T>);
    constexpr allocator_type get_allocator() const noexcept;
 
    // iterators
    constexpr iterator               begin() noexcept;
    constexpr const_iterator         begin() const noexcept;
    constexpr iterator               end() noexcept;
    constexpr const_iterator         end() const noexcept;
    constexpr reverse_iterator       rbegin() noexcept;
    constexpr const_reverse_iterator rbegin() const noexcept;
    constexpr reverse_iterator       rend() noexcept;
    constexpr const_reverse_iterator rend() const noexcept;
 
    constexpr const_iterator         cbegin() const noexcept;
    constexpr const_iterator         cend() const noexcept;
    constexpr const_reverse_iterator crbegin() const noexcept;
    constexpr const_reverse_iterator crend() const noexcept;
 
    // capacity
    [[nodiscard]] constexpr bool empty() const noexcept;
    constexpr size_type size() const noexcept;
    constexpr size_type max_size() const noexcept;
    constexpr size_type capacity() const noexcept;
    constexpr void      resize(size_type sz);
    constexpr void      resize(size_type sz, const T& c);
    constexpr void      reserve(size_type n);
    constexpr void      shrink_to_fit();
 
    // element access
    constexpr reference       operator[](size_type n);
    constexpr const_reference operator[](size_type n) const;
    constexpr const_reference at(size_type n) const;
    constexpr reference       at(size_type n);
    constexpr reference       front();
    constexpr const_reference front() const;
    constexpr reference       back();
    constexpr const_reference back() const;
 
    // data access
    constexpr T*       data() noexcept;
    constexpr const T* data() const noexcept;
 
    // modifiers
    template<class... Args> constexpr reference emplace_back(Args&&... args);
    constexpr void push_back(const T& x);
    constexpr void push_back(T&& x);
    template<__container_compatible_range<T> R>
      constexpr void append_range(R&& rg);
    constexpr void pop_back();
 
    template<class... Args> constexpr iterator emplace(const_iterator position,
                                                       Args&&... args);
    constexpr iterator insert(const_iterator position, const T& x);
    constexpr iterator insert(const_iterator position, T&& x);
    constexpr iterator insert(const_iterator position, size_type n, const T& x);
    template<class InputIt>
      constexpr iterator insert(const_iterator position,
                                InputIt first, InputIt last);
    template<__container_compatible_range<T> R>
      constexpr iterator insert_range(const_iterator position, R&& rg);
    constexpr iterator insert(const_iterator position, initializer_list<T> il);
    constexpr iterator erase(const_iterator position);
    constexpr iterator erase(const_iterator first, const_iterator last);
    constexpr void     swap(vector&)
      noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
               allocator_traits<Allocator>::is_always_equal::value);
    constexpr void     clear() noexcept;
  };
 
  template<class InputIt, class Allocator = allocator<__iter_value_type<InputIt>>>
    vector(InputIt, InputIt, Allocator = Allocator())
      -> vector<__iter_value_type<InputIt>, Allocator>;
 
  template<ranges::input_range R, class Allocator = allocator<ranges::range_value_t<R>>>
    vector(from_range_t, R&&, Allocator = Allocator())
      -> vector<ranges::range_value_t<R>, Allocator>;
}

Class template std::vector's specialization for bool 

namespace std {
  template<class Allocator>
  class vector<bool, Allocator> {
  public:
    // types
    using value_type             = bool;
    using allocator_type         = Allocator;
    using pointer                = /* implementation-defined */;
    using const_pointer          = /* implementation-defined */;
    using const_reference        = bool;
    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>;
 
    // bit reference
    class reference {
      friend class vector;
      constexpr reference() noexcept;
 
    public:
      constexpr reference(const reference&) = default;
      constexpr ~reference();
      constexpr operator bool() const noexcept;
      constexpr reference& operator=(bool x) noexcept;
      constexpr reference& operator=(const reference& x) noexcept;
      constexpr const reference& operator=(bool x) const noexcept;
      constexpr void flip() noexcept;   // flips the bit
    };
 
    // construct/copy/destroy
    constexpr vector() noexcept(noexcept(Allocator())) : vector(Allocator()) { }
    constexpr explicit vector(const Allocator&) noexcept;
    constexpr explicit vector(size_type n, const Allocator& = Allocator());
    constexpr vector(size_type n, const bool& value, const Allocator& = Allocator());
    template<class InputIt>
      constexpr vector(InputIt first, InputIt last, const Allocator& = Allocator());
    template<__container_compatible_range<bool> R>
      constexpr vector(from_range_t, R&& rg, const Allocator& = Allocator());
    constexpr vector(const vector& x);
    constexpr vector(vector&& x) noexcept;
    constexpr vector(const vector&, const type_identity_t<Allocator>&);
    constexpr vector(vector&&, const type_identity_t<Allocator>&);
    constexpr vector(initializer_list<bool>, const Allocator& = Allocator());
    constexpr ~vector();
    constexpr vector& operator=(const vector& x);
    constexpr vector& operator=(vector&& x)
      noexcept(
        allocator_traits<Allocator>::propagate_on_container_move_assignment::value ||
        allocator_traits<Allocator>::is_always_equal::value
      );
    constexpr vector& operator=(initializer_list<bool>);
    template<class InputIt>
      constexpr void assign(InputIt first, InputIt last);
    template<__container_compatible_range<bool> R>
      constexpr void assign_range(R&& rg);
    constexpr void assign(size_type n, const bool& t);
    constexpr void assign(initializer_list<bool>);
    constexpr allocator_type get_allocator() const noexcept;
 
    // iterators
    constexpr iterator               begin() noexcept;
    constexpr const_iterator         begin() const noexcept;
    constexpr iterator               end() noexcept;
    constexpr const_iterator         end() const noexcept;
    constexpr reverse_iterator       rbegin() noexcept;
    constexpr const_reverse_iterator rbegin() const noexcept;
    constexpr reverse_iterator       rend() noexcept;
    constexpr const_reverse_iterator rend() const noexcept;
 
    constexpr const_iterator         cbegin() const noexcept;
    constexpr const_iterator         cend() const noexcept;
    constexpr const_reverse_iterator crbegin() const noexcept;
    constexpr const_reverse_iterator crend() const noexcept;
 
    // capacity
    [[nodiscard]] constexpr bool empty() const noexcept;
    constexpr size_type size() const noexcept;
    constexpr size_type max_size() const noexcept;
    constexpr size_type capacity() const noexcept;
    constexpr void      resize(size_type sz, bool c = false);
    constexpr void      reserve(size_type n);
    constexpr void      shrink_to_fit();
 
    // element access
    constexpr reference       operator[](size_type n);
    constexpr const_reference operator[](size_type n) const;
    constexpr const_reference at(size_type n) const;
    constexpr reference       at(size_type n);
    constexpr reference       front();
    constexpr const_reference front() const;
    constexpr reference       back();
    constexpr const_reference back() const;
 
    // modifiers
    template<class... Args> constexpr reference emplace_back(Args&&... args);
    constexpr void push_back(const bool& x);
    template<__container_compatible_range<bool> R>
      constexpr void append_range(R&& rg);
    constexpr void pop_back();
    template<class... Args> constexpr iterator emplace(const_iterator position,
                                                       Args&&... args);
    constexpr iterator insert(const_iterator position, const bool& x);
    constexpr iterator insert(const_iterator position, size_type n, const bool& x);
    template<class InputIt>
      constexpr iterator insert(const_iterator position,
                                InputIt first, InputIt last);
    template<__container_compatible_range<bool> R>
      constexpr iterator insert_range(const_iterator position, R&& rg);
    constexpr iterator insert(const_iterator position, initializer_list<bool> il);
 
    constexpr iterator erase(const_iterator position);
    constexpr iterator erase(const_iterator first, const_iterator last);
    constexpr void swap(vector&)
      noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
               allocator_traits<Allocator>::is_always_equal::value);
    static constexpr void swap(reference x, reference y) noexcept;
    constexpr void flip() noexcept;     // flips all bits
    constexpr void clear() noexcept;
  };
}

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