C + + Deque (bidirectional queue)

C + + Deque ( bidirectional queuing ) is an optimized basic sequence container for adding and deleting operations on both ends of a sequence. It allows for faster random access, but it does not keep all objects in a contiguous block of memory like a vector, but instead uses multiple contiguous blocks of storage and keeps track of those blocks and their order in a mapping structure. Adding or removing elements to deque is a small cost. It does not need to reallocate space, so adding elements to the end is more efficient than vector.

In fact, Deque is a combination of the pros and cons of vectors and lists, which is a container between the two.

Deque Features of:

(1) Convenient random access, that is, support [] operator and vector.at (), but the performance of the vector is not good;

(2) can be inserted and deleted internally, but the performance is not the list;

(3) can be push, pop at both ends;

(4) Use more memory relative to Verctor.

A bidirectional queue is similar to a vector, but it allows for quick insertion and deletion of the container's head (as in the tail).

1.Constructors Create a new bidirectional queue

Grammar:

Deque ();//Create an empty bidirectional queue

Deque (size_type size);//Create a two-way queue of size

Deque (size_type num, const type &VAL); Place a copy of Num Val into the queue

Deque (const deque &from);//Create a content-like bidirectional queue from the From

Deque (input_iterator start, Input_iterator end);

Start and end-Creates a queue that holds elements from start to end.

2.Operators comparison and assignment bidirectional queue

You can use the [] operator to access a single element in a two-way queue

3.assign () Sets the value of the bidirectional queue

Grammar:

void assign (Input_iterator start, Input_iterator end);

The range indicated by start and end is a two-way queue assignment

void assign (Size num, const TYPE &val);//set to num val.

4.at () returns the specified element
Grammar:

Reference at (size_type POS); Returns a reference to the element on position Pos in a bidirectional queue

5.back () returns the last element

Grammar:

Reference back ();//Returns a reference that points to the last element in a bidirectional queue

6.begin () returns the iterator that points to the first element

Grammar:

Iterator begin ();//Returns an iterator that points to the first element of a bidirectional queue

7.clear () Delete all elements

8.empty () return True if the two-way queue is empty

9.end () returns an iterator pointing to the tail

10.erase () Delete an element

Grammar:

Iterator Erase (iterator POS); Delete an element at the POS location

Iterator Erase (iterator start, iterator end); Delete all elements between start and end

Returns the last element that points to a deleted element

11.front () returns a reference to the first element

12.get_allocator () returns the Configurator for the bidirectional queue

13.insert () inserting an element into a two-way queue

Grammar:

Iterator Insert (iterator pos, size_type num, const type &VAL); Num Val values are inserted in front of POS

void Insert (iterator pos, input_iterator start, Input_iterator end);

Inserting elements from start to end in front of POS

14.max_size () returns the maximum number of elements that a two-way queue can hold

15.pop_back () Delete the trailing element

16.pop_front () Delete the element of the head

17.push_back () Adds an element to the tail

18.push_front () Adds an element to the head

19.rbegin () returns a reverse iterator pointing to the tail

20.rend () returns a reverse iterator pointing to the head

21.resize () Change the size of the two-way queue

22.size () returns the number of elements in a two-way queue

23.swap () and another bidirectional queue interchange element

Grammar:

void swap (deque &target);//swap target and current bidirectional queue elements

C + + Deque (bidirectional queue)