23 Containers library [containers]

23.3 Sequence containers [sequences]

23.3.6 Class template vector [vector] Class template vector overview [vector.overview]

A vector is a sequence container that supports random access iterators. In addition, it supports (amortized) constant time insert and erase operations at the end; insert and erase in the middle take linear time. Storage management is handled automatically, though hints can be given to improve efficiency. The elements of a vector are stored contiguously, meaning that if v is a vector<T, Allocator> where T is some type other than bool, then it obeys the identity &v[n] == &v[0] + n for all 0 <= n < v.size().

A vector satisfies all of the requirements of a container and of a reversible container (given in two tables in [container.requirements]), of a sequence container, including most of the optional sequence container requirements ([sequence.reqmts]), and of an allocator-aware container (Table [tab:containers.allocatoraware]). The exceptions are the push_front, pop_front, and emplace_front member functions, which are not provided. Descriptions are provided here only for operations on vector that are not described in one of these tables or for operations where there is additional semantic information.

namespace std {
  template <class T, class Allocator = allocator<T> >
  class vector {
    // types:
    typedef value_type&                           reference;
    typedef const value_type&                     const_reference;
    typedef implementation-defined                iterator;       // see [container.requirements]
    typedef implementation-defined                const_iterator; // see [container.requirements]
    typedef implementation-defined                size_type;      // see [container.requirements]
    typedef implementation-defined                difference_type;// see [container.requirements]
    typedef T                                     value_type;
    typedef Allocator                             allocator_type;
    typedef typename allocator_traits<Allocator>::pointer           pointer;
    typedef typename allocator_traits<Allocator>::const_pointer     const_pointer;
    typedef std::reverse_iterator<iterator>       reverse_iterator;
    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;

    // [vector.cons], construct/copy/destroy:
    explicit vector(const Allocator& = Allocator());
    explicit vector(size_type n);
    vector(size_type n, const T& value, const Allocator& = Allocator());
    template <class InputIterator>
      vector(InputIterator first, InputIterator last,
             const Allocator& = Allocator());
    vector(const vector& x);
    vector(const vector&, const Allocator&);
    vector(vector&&, const Allocator&);
    vector(initializer_list<T>, const Allocator& = Allocator());
    vector& operator=(const vector& x);
    vector& operator=(vector&& x);
    vector& operator=(initializer_list<T>);
    template <class InputIterator>
      void assign(InputIterator first, InputIterator last);
    void assign(size_type n, const T& u);
    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;

    // [vector.capacity], capacity:
    size_type size() const noexcept;
    size_type max_size() const noexcept;
    void      resize(size_type sz);
    void      resize(size_type sz, const T& c);
    size_type capacity() const noexcept;
    bool      empty() const noexcept;
    void      reserve(size_type n);
    void      shrink_to_fit();

    // element access:
    reference       operator[](size_type n);
    const_reference operator[](size_type n) const;
    const_reference at(size_type n) const;
    reference       at(size_type n);
    reference       front();
    const_reference front() const;
    reference       back();
    const_reference back() const;

    // [vector.data], data access
    T*         data() noexcept;
    const T*  data() const noexcept;

    // [vector.modifiers], modifiers:
    template <class... Args> void emplace_back(Args&&... args);
    void push_back(const T& x);
    void push_back(T&& x);
    void pop_back();

    template <class... Args> iterator emplace(const_iterator position, Args&&... args);
    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 InputIterator>
        iterator insert(const_iterator position,
                        InputIterator first, InputIterator last);
    iterator     insert(const_iterator position, initializer_list<T> il);
    iterator erase(const_iterator position);
    iterator erase(const_iterator first, const_iterator last);
    void     swap(vector&);
    void     clear() noexcept;

  template <class T, class Allocator>
    bool operator==(const vector<T,Allocator>& x, const vector<T,Allocator>& y);
  template <class T, class Allocator>
    bool operator< (const vector<T,Allocator>& x, const vector<T,Allocator>& y);
  template <class T, class Allocator>
    bool operator!=(const vector<T,Allocator>& x, const vector<T,Allocator>& y);
  template <class T, class Allocator>
    bool operator> (const vector<T,Allocator>& x, const vector<T,Allocator>& y);
  template <class T, class Allocator>
    bool operator>=(const vector<T,Allocator>& x, const vector<T,Allocator>& y);
  template <class T, class Allocator>
    bool operator<=(const vector<T,Allocator>& x, const vector<T,Allocator>& y);

  // [vector.special], specialized algorithms:
  template <class T, class Allocator>
    void swap(vector<T,Allocator>& x, vector<T,Allocator>& y);