# Standard library header <vector>

From cppreference.com
< cpp‎ | header

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
vector | dynamic contiguous array (class template)
vector<bool> | space-efficient dynamic bitset (class template specialization)
std::hash<std::vector<bool>> (C++11) | hash support for std::vector<bool> (class template specialization)
##### Forward declarations
Defined in header `<functional>`
hash (C++11) | hash function object (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 in the vector (function template)
std::swap(std::vector) | specializes the std::swap algorithm (function template)
erase(std::vector)erase_if(std::vector) (C++20) | erases all elements satisfying specific criteria (function template)
##### Range access
begin cbegin (C++11)(C++14) | returns an iterator to the beginning of a container or array (function template)
end cend (C++11)(C++14) | returns an iterator to the end of a container or array (function template)
rbegin crbegin (C++14) | returns a reverse iterator to the beginning of a container or array (function template)
rend crend (C++14) | returns a reverse end iterator for a container or array (function template)
size ssize (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 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;
      };
    }

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/header/vector&oldid=146375"