std::deque - Man Page

typedef _Alloc allocator_type
typedef _Base::const_iterator const_iterator
typedef _Alloc_traits::const_pointer const_pointer
typedef _Alloc_traits::const_reference const_reference
typedef std::reverse_iterator< const_iterator > const_reverse_iterator
typedef ptrdiff_t difference_type
typedef _Base::iterator iterator
typedef _Alloc_traits::pointer pointer
typedef _Alloc_traits::reference reference
typedef std::reverse_iterator< iterator > reverse_iterator
typedef size_t size_type
typedef _Tp value_type

deque ()=default
Creates a deque with no elements.
template<typename _InputIterator , typename  = std::_RequireInputIter<_InputIterator>> deque (_InputIterator __first, _InputIterator __last, const allocator_type &__a=allocator_type())
Builds a deque from a range.
deque (const allocator_type &__a)
Creates a deque with no elements.
deque (const deque &__x)
Deque copy constructor.
deque (const deque &__x, const __type_identity_t< allocator_type > &__a)
Copy constructor with alternative allocator.
deque (deque &&)=default
Deque move constructor.
deque (deque &&__x, const __type_identity_t< allocator_type > &__a)
Move constructor with alternative allocator.
deque (initializer_list< value_type > __l, const allocator_type &__a=allocator_type())
Builds a deque from an initializer list.
deque (size_type __n, const allocator_type &__a=allocator_type())
Creates a deque with default constructed elements.
deque (size_type __n, const value_type &__value, const allocator_type &__a=allocator_type())
Creates a deque with copies of an exemplar element.
~deque ()
template<typename _InputIterator , typename  = std::_RequireInputIter<_InputIterator>> void assign (_InputIterator __first, _InputIterator __last)
Assigns a range to a deque.
void assign (initializer_list< value_type > __l)
Assigns an initializer list to a deque.
void assign (size_type __n, const value_type &__val)
Assigns a given value to a deque.
reference at (size_type __n)
Provides access to the data contained in the deque.
const_reference at (size_type __n) const
Provides access to the data contained in the deque.
const_reference back () const noexcept
reference back () noexcept
const_iterator begin () const noexcept
iterator begin () noexcept
const_iterator cbegin () const noexcept
const_iterator cend () const noexcept
void clear () noexcept
const_reverse_iterator crbegin () const noexcept
const_reverse_iterator crend () const noexcept
template<typename... _Args> iterator emplace (const_iterator __position, _Args &&... __args)
Inserts an object in deque before specified iterator.
template<typename... _Args> reference emplace_back (_Args &&... __args)
template<typename... _Args> reference emplace_front (_Args &&... __args)
bool empty () const noexcept
const_iterator end () const noexcept
iterator end () noexcept
iterator erase (const_iterator __first, const_iterator __last)
Remove a range of elements.
iterator erase (const_iterator __position)
Remove element at given position.
const_reference front () const noexcept
reference front () noexcept
allocator_type get_allocator () const noexcept
Get a copy of the memory allocation object.
iterator insert (const_iterator __p, initializer_list< value_type > __l)
Inserts an initializer list into the deque.
template<typename _InputIterator , typename  = std::_RequireInputIter<_InputIterator>> iterator insert (const_iterator __position, _InputIterator __first, _InputIterator __last)
Inserts a range into the deque.
iterator insert (const_iterator __position, const value_type &__x)
Inserts given value into deque before specified iterator.
iterator insert (const_iterator __position, size_type __n, const value_type &__x)
Inserts a number of copies of given data into the deque.
iterator insert (const_iterator __position, value_type &&__x)
Inserts given rvalue into deque before specified iterator.
size_type max_size () const noexcept
deque & operator= (const deque &__x)
Deque assignment operator.
deque & operator= (deque &&__x) noexcept(_Alloc_traits::_S_always_equal())
Deque move assignment operator.
deque & operator= (initializer_list< value_type > __l)
Assigns an initializer list to a deque.
const_reference operator[] (size_type __n) const noexcept
Subscript access to the data contained in the deque.
reference operator[] (size_type __n) noexcept
Subscript access to the data contained in the deque.
void pop_back () noexcept
Removes last element.
void pop_front () noexcept
Removes first element.
void push_back (const value_type &__x)
Add data to the end of the deque.
void push_back (value_type &&__x)
void push_front (const value_type &__x)
Add data to the front of the deque.
void push_front (value_type &&__x)
const_reverse_iterator rbegin () const noexcept
reverse_iterator rbegin () noexcept
const_reverse_iterator rend () const noexcept
reverse_iterator rend () noexcept
void resize (size_type __new_size)
Resizes the deque to the specified number of elements.
void resize (size_type __new_size, const value_type &__x)
Resizes the deque to the specified number of elements.
void shrink_to_fit () noexcept
size_type size () const noexcept
void swap (deque &__x) noexcept
Swaps data with another deque.

enum { _S_initial_map_size }
typedef __gnu_cxx::__alloc_traits< _Map_alloc_type > _Map_alloc_traits
typedef _Alloc_traits::template rebind< _Ptr >::other _Map_alloc_type
typedef _Alloc_traits::pointer _Ptr
typedef _Alloc_traits::const_pointer _Ptr_const

template<typename _ForwardIterator > void _M_assign_aux (_ForwardIterator __first, _ForwardIterator __last, std::forward_iterator_tag)
template<typename _InputIterator > void _M_assign_aux (_InputIterator __first, _InputIterator __last, std::input_iterator_tag)
void _M_deallocate_map (_Map_pointer __p, size_t __n) noexcept
void _M_default_append (size_type __n)
void _M_default_initialize ()
template<typename _Alloc1 > void _M_destroy_data (iterator __first, iterator __last, const _Alloc1 &)
void _M_destroy_data (iterator __first, iterator __last, const std::allocator< _Tp > &)
void _M_destroy_data_aux (iterator __first, iterator __last)
iterator _M_erase (iterator __first, iterator __last)
iterator _M_erase (iterator __pos)
void _M_erase_at_begin (iterator __pos)
void _M_erase_at_end (iterator __pos)
void _M_fill_assign (size_type __n, const value_type &__val)
void _M_fill_initialize (const value_type &__value)
Fills the deque with copies of value.
void _M_fill_insert (iterator __pos, size_type __n, const value_type &__x)
_Map_alloc_type _M_get_map_allocator () const noexcept
template<typename... _Args> iterator _M_insert_aux (iterator __pos, _Args &&... __args)
template<typename _ForwardIterator > void _M_insert_aux (iterator __pos, _ForwardIterator __first, _ForwardIterator __last, size_type __n)
void _M_insert_aux (iterator __pos, size_type __n, const value_type &__x)
void _M_move_assign1 (deque &&__x, false_type)
void _M_move_assign1 (deque &&__x, true_type) noexcept
void _M_move_assign2 (deque &&__x, false_type)
void _M_move_assign2 (deque &&__x, true_type)
void _M_range_check (size_type __n) const
Safety check used only from at().
template<typename _ForwardIterator > void _M_range_insert_aux (iterator __pos, _ForwardIterator __first, _ForwardIterator __last, std::forward_iterator_tag)
template<typename _InputIterator > void _M_range_insert_aux (iterator __pos, _InputIterator __first, _InputIterator __last, std::input_iterator_tag)
template<typename... _Args> void _M_replace_map (_Args &&... __args)
bool _M_shrink_to_fit ()

template<typename _InputIterator > void _M_range_initialize (_InputIterator __first, _InputIterator __last, std::input_iterator_tag)
Fills the deque with whatever is in [first,last).
template<typename _ForwardIterator > void _M_range_initialize (_ForwardIterator __first, _ForwardIterator __last, std::forward_iterator_tag)
Fills the deque with whatever is in [first,last).

template<typename... _Args> void _M_push_back_aux (_Args &&... __args)
Helper functions for push_* and pop_*.
template<typename... _Args> void _M_push_front_aux (_Args &&... __args)
Helper functions for push_* and pop_*.
void _M_pop_back_aux ()
Helper functions for push_* and pop_*.
void _M_pop_front_aux ()
Helper functions for push_* and pop_*.

iterator _M_reserve_elements_at_front (size_type __n)
Memory-handling helpers for the previous internal insert functions.
iterator _M_reserve_elements_at_back (size_type __n)
Memory-handling helpers for the previous internal insert functions.
void _M_new_elements_at_front (size_type __new_elements)
Memory-handling helpers for the previous internal insert functions.
void _M_new_elements_at_back (size_type __new_elements)
Memory-handling helpers for the previous internal insert functions.

void _M_reserve_map_at_back (size_type __nodes_to_add=1)
Memory-handling helpers for the major map.
void _M_reserve_map_at_front (size_type __nodes_to_add=1)
Memory-handling helpers for the major map.
void _M_reallocate_map (size_type __nodes_to_add, bool __add_at_front)
Memory-handling helpers for the major map.

static size_t _S_check_init_len (size_t __n, const allocator_type &__a)
static size_type _S_max_size (const _Tp_alloc_type &__a) noexcept

class std::deque< _Tp, _Alloc >"A standard container using fixed-size memory allocation and constant-time manipulation of elements at either end.

Template Parameters

Meets the requirements of a container, a reversible container, and a sequence, including the optional sequence requirements.

In previous HP/SGI versions of deque, there was an extra template parameter so users could control the node size. This extension turned out to violate the C++ standard (it can be detected using template template parameters), and it was removed.

Here's how a deque<Tp> manages memory. Each deque has 4 members:

• Tp** _M_map
• size_t _M_map_size
• iterator _M_start, _M_finish

map_size is at least 8. map is an array of map_size pointers-to-nodes. (The name map has nothing to do with the std::map class, and nodes should not be confused with std::list's usage of node.)

A node has no specific type name as such, but it is referred to as node in this file. It is a simple array-of-Tp. If Tp is very large, there will be one Tp element per node (i.e., an array of one). For non-huge Tp's, node size is inversely related to Tp size: the larger the Tp, the fewer Tp's will fit in a node. The goal here is to keep the total size of a node relatively small and constant over different Tp's, to improve allocator efficiency.

Not every pointer in the map array will point to a node. If the initial number of elements in the deque is small, the /middle/ map pointers will be valid, and the ones at the edges will be unused. This same situation will arise as the map grows: available map pointers, if any, will be on the ends. As new nodes are created, only a subset of the map's pointers need to be copied outward.

Class invariants:

·

For any nonsingular iterator i:

 ·

i.node points to a member of the map array. (Yes, you read that correctly: i.node does not actually point to a node.) The member of the map array is what actually points to the node.

 ·

i.first == *(i.node) (This points to the node (first Tp element).)

 ·

i.last == i.first + node_size

 ·

i.cur is a pointer in the range [i.first, i.last). NOTE: the implication of this is that i.cur is always a dereferenceable pointer, even if i is a past-the-end iterator.

·

Start and Finish are always nonsingular iterators. NOTE: this means that an empty deque must have one node, a deque with <N elements (where N is the node buffer size) must have one node, a deque with N through (2N-1) elements must have two nodes, etc.

·

For every node other than start.node and finish.node, every element in the node is an initialized object. If start.node == finish.node, then [start.cur, finish.cur) are initialized objects, and the elements outside that range are uninitialized storage. Otherwise, [start.cur, start.last) and [finish.first, finish.cur) are initialized objects, and [start.first, start.cur) and [finish.cur, finish.last) are uninitialized storage.

·

[map, map + map_size) is a valid, non-empty range.

·

[start.node, finish.node] is a valid range contained within [map, map + map_size).

·

A pointer in the range [map, map + map_size) points to an allocated node if and only if the pointer is in the range [start.node, finish.node].

Here's the magic: nothing in deque is aware of the discontiguous storage!

The memory setup and layout occurs in the parent, _Base, and the iterator class is entirely responsible for leaping from one node to the next. All the implementation routines for deque itself work only through the start and finish iterators. This keeps the routines simple and sane, and we can use other standard algorithms as well.

Creates a deque with no elements.

Creates a deque with no elements.

Parameters

Creates a deque with default constructed elements.

Parameters

This constructor fills the deque with n default constructed elements.

Creates a deque with copies of an exemplar element.

Parameters

This constructor fills the deque with __n copies of __value.

References std::deque< _Tp, _Alloc >::_M_fill_initialize().

Deque copy constructor.

Parameters

The newly-created deque uses a copy of the allocator object used by __x (unless the allocator traits dictate a different object).

References std::deque< _Tp, _Alloc >::begin(), and std::deque< _Tp, _Alloc >::end().

Deque move constructor. The newly-created deque contains the exact contents of the moved instance. The contents of the moved instance are a valid, but unspecified deque.

Copy constructor with alternative allocator.

References std::deque< _Tp, _Alloc >::begin(), and std::deque< _Tp, _Alloc >::end().

Move constructor with alternative allocator.

Builds a deque from an initializer list.

Parameters

Create a deque consisting of copies of the elements in the initializer_list __l.

This will call the element type's copy constructor N times (where N is __l.size()) and do no memory reallocation.

References std::deque< _Tp, _Alloc >::_M_range_initialize().

Builds a deque from a range.

Parameters

Create a deque consisting of copies of the elements from [__first, __last).

If the iterators are forward, bidirectional, or random-access, then this will call the elements' copy constructor N times (where N is distance(__first,__last)) and do no memory reallocation. But if only input iterators are used, then this will do at most 2N calls to the copy constructor, and logN memory reallocations.

References std::__iterator_category(), and std::deque< _Tp, _Alloc >::_M_range_initialize().

The dtor only erases the elements, and note that if the elements themselves are pointers, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

References std::deque< _Tp, _Alloc >::begin(), and std::deque< _Tp, _Alloc >::end().

Fills the deque with copies of value.

Parameters

Returns

Nothing.

Precondition

This function is called only when the user provides an explicit size (with or without an explicit exemplar value).

References std::_Destroy().

Referenced by std::deque< _Tp, _Alloc >::deque().

Memory-handling helpers for the previous internal insert functions.

References std::size().

Referenced by std::deque< _Tp, _Alloc >::_M_reserve_elements_at_back().

Memory-handling helpers for the previous internal insert functions.

References std::size().

Referenced by std::deque< _Tp, _Alloc >::_M_reserve_elements_at_front().

Helper functions for push_* and pop_*.

Referenced by std::deque< _Tp, _Alloc >::pop_back().

Helper functions for push_* and pop_*.

Referenced by std::deque< _Tp, _Alloc >::pop_front().

Helper functions for push_* and pop_*.

References std::forward(), and std::size().

Referenced by std::deque< _Tp, _Alloc >::push_back().

Helper functions for push_* and pop_*.

References std::forward(), and std::size().

Referenced by std::deque< _Tp, _Alloc >::push_front().

Safety check used only from at().

References std::deque< _Tp, _Alloc >::size().

Referenced by std::deque< _Tp, _Alloc >::at(), and std::deque< _Tp, _Alloc >::at().

Fills the deque with whatever is in [first,last).

Parameters

Returns

Nothing.

If the iterators are actually forward iterators (or better), then the memory layout can be done all at once. Else we move forward using push_back on each value from the iterator.

References std::_Destroy(), std::advance(), and std::distance().

Fills the deque with whatever is in [first,last).

Parameters

Returns

Nothing.

If the iterators are actually forward iterators (or better), then the memory layout can be done all at once. Else we move forward using push_back on each value from the iterator.

Referenced by std::deque< _Tp, _Alloc >::deque(), and std::deque< _Tp, _Alloc >::deque().

Memory-handling helpers for the major map. Makes sure the _M_map has space for new nodes. Does not actually add the nodes. Can invalidate _M_map pointers. (And consequently, deque iterators.)

References std::max().

Referenced by std::deque< _Tp, _Alloc >::_M_reserve_map_at_back(), and std::deque< _Tp, _Alloc >::_M_reserve_map_at_front().

Memory-handling helpers for the previous internal insert functions.

References std::deque< _Tp, _Alloc >::_M_new_elements_at_back().

Memory-handling helpers for the previous internal insert functions.

References std::deque< _Tp, _Alloc >::_M_new_elements_at_front().

Memory-handling helpers for the major map. Makes sure the _M_map has space for new nodes. Does not actually add the nodes. Can invalidate _M_map pointers. (And consequently, deque iterators.)

References std::deque< _Tp, _Alloc >::_M_reallocate_map().

Memory-handling helpers for the major map. Makes sure the _M_map has space for new nodes. Does not actually add the nodes. Can invalidate _M_map pointers. (And consequently, deque iterators.)

References std::deque< _Tp, _Alloc >::_M_reallocate_map().

Assigns a range to a deque.

Parameters

This function fills a deque with copies of the elements in the range [__first,__last).

Note that the assignment completely changes the deque and that the resulting deque's size is the same as the number of elements assigned.

References std::__iterator_category().

Assigns an initializer list to a deque.

Parameters

This function fills a deque with copies of the elements in the initializer_list __l.

Note that the assignment completely changes the deque and that the resulting deque's size is the same as the number of elements assigned.

Assigns a given value to a deque.

Parameters

This function fills a deque with n copies of the given value. Note that the assignment completely changes the deque and that the resulting deque's size is the same as the number of elements assigned.

Provides access to the data contained in the deque.

Parameters

Returns

Read/write reference to data.

Exceptions

std::out_of_range If __n is an invalid index.

This function provides for safer data access. The parameter is first checked that it is in the range of the deque. The function throws out_of_range if the check fails.

References std::deque< _Tp, _Alloc >::_M_range_check().

Provides access to the data contained in the deque.

Parameters

Returns

Read-only (constant) reference to data.

Exceptions

std::out_of_range If __n is an invalid index.

This function provides for safer data access. The parameter is first checked that it is in the range of the deque. The function throws out_of_range if the check fails.

References std::deque< _Tp, _Alloc >::_M_range_check().

Returns a read-only (constant) reference to the data at the last element of the deque.

References std::deque< _Tp, _Alloc >::end().

Returns a read/write reference to the data at the last element of the deque.

References std::deque< _Tp, _Alloc >::end().

Returns a read-only (constant) iterator that points to the first element in the deque. Iteration is done in ordinary element order.

Returns a read/write iterator that points to the first element in the deque. Iteration is done in ordinary element order.

Referenced by std::deque< _Tp, _Alloc >::deque(), std::deque< _Tp, _Alloc >::deque(), std::deque< _Tp, _Alloc >::~deque(), std::deque< _Tp, _Alloc >::clear(), std::deque< _Tp, _Alloc >::front(), std::deque< _Tp, _Alloc >::front(), std::deque< _Tp, _Alloc >::insert(), std::deque< _Tp, _Alloc >::insert(), std::deque< _Tp, _Alloc >::insert(), std::operator<=>(), and std::deque< _Tp, _Alloc >::operator=().

Returns a read-only (constant) iterator that points to the first element in the deque. Iteration is done in ordinary element order.

Referenced by std::deque< _Tp, _Alloc >::insert(), std::deque< _Tp, _Alloc >::insert(), and std::deque< _Tp, _Alloc >::insert().

Returns a read-only (constant) iterator that points one past the last element in the deque. Iteration is done in ordinary element order.

Erases all the elements. Note that this function only erases the elements, and that if the elements themselves are pointers, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

References std::deque< _Tp, _Alloc >::begin().

Returns a read-only (constant) reverse iterator that points to the last element in the deque. Iteration is done in reverse element order.

Returns a read-only (constant) reverse iterator that points to one before the first element in the deque. Iteration is done in reverse element order.

Inserts an object in deque before specified iterator.

Parameters

Returns

An iterator that points to the inserted data.

This function will insert an object of type T constructed with T(std::forward<Args>(args)...) before the specified location.

References std::forward().

Referenced by std::deque< _Tp, _Alloc >::insert().

Returns true if the deque is empty. (Thus begin() would equal end().)

Returns a read-only (constant) iterator that points one past the last element in the deque. Iteration is done in ordinary element order.

Returns a read/write iterator that points one past the last element in the deque. Iteration is done in ordinary element order.

Referenced by std::deque< _Tp, _Alloc >::deque(), std::deque< _Tp, _Alloc >::deque(), std::deque< _Tp, _Alloc >::~deque(), std::deque< _Tp, _Alloc >::back(), std::deque< _Tp, _Alloc >::back(), std::operator<=>(), and std::deque< _Tp, _Alloc >::operator=().

Remove a range of elements.

Parameters

Returns

An iterator pointing to the element pointed to by last prior to erasing (or end()).

This function will erase the elements in the range [__first,__last) and shorten the deque accordingly.

The user is cautioned that this function only erases the elements, and that if the elements themselves are pointers, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

Remove element at given position.

Parameters

Returns

An iterator pointing to the next element (or end()).

This function will erase the element at the given position and thus shorten the deque by one.

The user is cautioned that this function only erases the element, and that if the element is itself a pointer, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

Returns a read-only (constant) reference to the data at the first element of the deque.

References std::deque< _Tp, _Alloc >::begin().

Returns a read/write reference to the data at the first element of the deque.

References std::deque< _Tp, _Alloc >::begin().

Get a copy of the memory allocation object.

Referenced by std::deque< _Tp, _Alloc >::operator=().

Inserts an initializer list into the deque.

Parameters

Returns

An iterator that points to the inserted data.

This function will insert copies of the data in the initializer_list __l into the deque before the location specified by __p. This is known as list insert.

References std::deque< _Tp, _Alloc >::begin(), and std::deque< _Tp, _Alloc >::cbegin().

Inserts a range into the deque.

Parameters

Returns

An iterator that points to the inserted data.

This function will insert copies of the data in the range [__first,__last) into the deque before the location specified by __position. This is known as range insert.

References std::__iterator_category(), std::deque< _Tp, _Alloc >::begin(), and std::deque< _Tp, _Alloc >::cbegin().

Inserts given value into deque before specified iterator.

Parameters

Returns

An iterator that points to the inserted data.

This function will insert a copy of the given value before the specified location.

Inserts a number of copies of given data into the deque.

Parameters

Returns

An iterator that points to the inserted data.

This function will insert a specified number of copies of the given data before the location specified by __position.

References std::deque< _Tp, _Alloc >::begin(), and std::deque< _Tp, _Alloc >::cbegin().

Inserts given rvalue into deque before specified iterator.

Parameters

Returns

An iterator that points to the inserted data.

This function will insert a copy of the given rvalue before the specified location.

References std::deque< _Tp, _Alloc >::emplace(), and std::move().

Returns the size() of the largest possible deque.

Deque assignment operator.

Parameters

All the elements of x are copied.

The newly-created deque uses a copy of the allocator object used by __x (unless the allocator traits dictate a different object).

References std::__addressof(), std::deque< _Tp, _Alloc >::begin(), std::deque< _Tp, _Alloc >::end(), std::deque< _Tp, _Alloc >::get_allocator(), std::deque< _Tp, _Alloc >::size(), and std::size().

Deque move assignment operator.

Parameters

The contents of __x are moved into this deque (without copying, if the allocators permit it). __x is a valid, but unspecified deque.

References std::move().

Assigns an initializer list to a deque.

Parameters

This function fills a deque with copies of the elements in the initializer_list __l.

Note that the assignment completely changes the deque and that the resulting deque's size is the same as the number of elements assigned.

Subscript access to the data contained in the deque.

Parameters

Returns

Read-only (constant) reference to data.

This operator allows for easy, array-style, data access. Note that data access with this operator is unchecked and out_of_range lookups are not defined. (For checked lookups see at().)

Subscript access to the data contained in the deque.

Parameters

Returns

Read/write reference to data.

This operator allows for easy, array-style, data access. Note that data access with this operator is unchecked and out_of_range lookups are not defined. (For checked lookups see at().)

Removes last element. This is a typical stack operation. It shrinks the deque by one.

Note that no data is returned, and if the last element's data is needed, it should be retrieved before pop_back() is called.

References std::deque< _Tp, _Alloc >::_M_pop_back_aux().

Removes first element. This is a typical stack operation. It shrinks the deque by one.

Note that no data is returned, and if the first element's data is needed, it should be retrieved before pop_front() is called.

References std::deque< _Tp, _Alloc >::_M_pop_front_aux().

Add data to the end of the deque.

Parameters

This is a typical stack operation. The function creates an element at the end of the deque and assigns the given data to it. Due to the nature of a deque this operation can be done in constant time.

References std::deque< _Tp, _Alloc >::_M_push_back_aux().

Add data to the front of the deque.

Parameters

This is a typical stack operation. The function creates an element at the front of the deque and assigns the given data to it. Due to the nature of a deque this operation can be done in constant time.

References std::deque< _Tp, _Alloc >::_M_push_front_aux().

Returns a read-only (constant) reverse iterator that points to the last element in the deque. Iteration is done in reverse element order.

Returns a read/write reverse iterator that points to the last element in the deque. Iteration is done in reverse element order.

Returns a read-only (constant) reverse iterator that points to one before the first element in the deque. Iteration is done in reverse element order.

Returns a read/write reverse iterator that points to one before the first element in the deque. Iteration is done in reverse element order.

Resizes the deque to the specified number of elements.

Parameters

This function will resize the deque to the specified number of elements. If the number is smaller than the deque's current size the deque is truncated, otherwise default constructed elements are appended.

References std::deque< _Tp, _Alloc >::size().

Resizes the deque to the specified number of elements.

Parameters

This function will resize the deque to the specified number of elements. If the number is smaller than the deque's current size the deque is truncated, otherwise the deque is extended and new elements are populated with given data.

References std::deque< _Tp, _Alloc >::size().

A non-binding request to reduce memory use.

Returns the number of elements in the deque.

Referenced by std::deque< _Tp, _Alloc >::_M_range_check(), std::operator<=>(), std::deque< _Tp, _Alloc >::operator=(), std::deque< _Tp, _Alloc >::resize(), and std::deque< _Tp, _Alloc >::resize().

Swaps data with another deque.

Parameters

This exchanges the elements between two deques in constant time. (Four pointers, so it should be quite fast.) Note that the global std::swap() function is specialized such that std::swap(d1,d2) will feed to this function.

Whether the allocators are swapped depends on the allocator traits.