std::deque
| Defined in header  <deque> | ||
| template<     class T, | ||
std::deque (double-ended queue) is an indexed sequence container that allows fast insertion and deletion at both its beginning and its end. In addition, insertion and deletion at either end of a deque never invalidates pointers or references to the rest of the elements.
As opposed to std::vector, the elements of a deque are not stored contiguously: typical implementations use a sequence of individually allocated fixed-size arrays.
The storage of a deque is automatically expanded and contracted as needed. Expansion of a deque is cheaper than the expansion of a std::vector because it does not involve copying of the existing elements to a new memory location.
The complexity (efficiency) of common operations on deques is as follows:
- Random access - constant O(1)
- Insertion or removal of elements at the end or beginning - amortized constant O(1)
- Insertion or removal of elements - linear O(n)
std::deque meets the requirements of Container, AllocatorAwareContainer, SequenceContainer and ReversibleContainer.
| Contents | 
[edit] Template parameters
| T | - | The type of the elements. 
 
 | ||||
| Allocator | - | An allocator that is used to acquire memory to store the elements. The type must meet the requirements of Allocator. | 
[edit] Iterator invalidation
| This section is incomplete | 
There are still a few inaccuracies in this section.
| Operations | Invalidated | 
|---|---|
| All read only operations, swap, std::swap | Never | 
| shrink_to_fit, clear, insert, emplace, push_back, emplace_back | Always | 
| erase | If erasing at beginning or end - only erased elements. Otherwise - all iterators are invalidated. | 
| resize | Only if the new size is bigger than the old one. | 
| pop_back, pop_front | Only to the element erased | 
[edit] Notes
- Under some circumstances, references are not invalidated by insert and emplace.
- push_back and emplace_back do not invalidate any references.
[edit] Member types
| Member type | Definition | ||||
| value_type | T | ||||
| allocator_type | Allocator | ||||
| size_type | Unsigned integral type (usually std::size_t) | ||||
| difference_type | Signed integer type (usually std::ptrdiff_t) | ||||
| reference | 
 | ||||
| const_reference | 
 | ||||
| pointer | 
 | ||||
| const_pointer | 
 | ||||
| iterator | RandomAccessIterator | ||||
| const_iterator | Constant random access iterator | ||||
| reverse_iterator | std::reverse_iterator<iterator> | ||||
| const_reverse_iterator | std::reverse_iterator<const_iterator> | 
[edit] Member functions
| constructs the deque(public member function) | |
| destructs the deque(public member function) | |
| assigns values to the container (public member function) | |
| assigns values to the container (public member function) | |
| returns the associated allocator (public member function) | |
| Element access | |
| access specified element with bounds checking (public member function) | |
| access specified element (public member function) | |
| access the first element (public member function) | |
| access the last element (public member function) | |
| Iterators | |
| returns an iterator to the beginning (public member function) | |
| returns an iterator to the end (public member function) | |
| returns a reverse iterator to the beginning (public member function) | |
| returns a reverse iterator to the end (public member function) | |
| Capacity | |
| checks whether the container is empty (public member function) | |
| returns the number of elements (public member function) | |
| returns the maximum possible number of elements (public member function) | |
| (C++11) | reduces memory usage by freeing unused memory (public member function) | 
| Modifiers | |
| clears the contents (public member function) | |
| inserts elements (public member function) | |
| (C++11) | constructs element in-place (public member function) | 
| erases elements (public member function) | |
| adds elements to the end (public member function) | |
| (C++11) | constructs elements in-place at the end (public member function) | 
| removes the last element (public member function) | |
| inserts elements to the beginning (public member function) | |
| (C++11) | constructs elements in-place at the beginning (public member function) | 
| removes the first element (public member function) | |
| changes the number of elements stored (public member function) | |
| swaps the contents (public member function) | |
[edit] Non-member functions
| lexicographically compares the values in the deque (function template) | |
| specializes the std::swap algorithm (function template) | 


