std::deque::deque

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

 

std::deque

Member functions

deque::deque

deque::~deque

deque::operator=

deque::assign

deque::get_allocator

Element access

deque::front

deque::back

Iterators

deque::begindeque::cbegin (C++11)

deque::enddeque::cend (C++11)

deque::rbegindeque::crbegin (C++11)

deque::renddeque::crend (C++11)

Capacity

deque::empty

deque::size

deque::max_size

deque::shrink_to_fit

Modifiers

deque::clear

deque::insert

deque::emplace

deque::erase

deque::push_front

deque::emplace_front

deque::pop_front

deque::push_back

deque::emplace_back

deque::pop_back

deque::resize

deque::swap

 

	(1)
explicit deque( const Allocator& alloc = Allocator() );			(until C++14)
deque() : deque( Allocator() ) {} explicit deque( const Allocator& alloc );			(since C++14)
		(2)
explicit deque( size_type count,                 const T& value = T(),                 const Allocator& alloc = Allocator());				(until C++11)
deque( size_type count,                 const T& value,                 const Allocator& alloc = Allocator());				(since C++11)
			(3)
explicit deque( size_type count );					(since C++11) (until C++14)
explicit deque( size_type count, const Allocator& alloc = Allocator() );					(since C++14)
template< class InputIt > deque( InputIt first, InputIt last,        const Allocator& alloc = Allocator() );				(4)
deque( const deque& other );				(5)
deque( const deque& other, const Allocator& alloc );				(5)	(since C++11)
deque( deque&& other );				(6)	(since C++11)
deque( deque&& other, const Allocator& alloc );				(7)	(since C++11)
deque( std::initializer_list<T> init,        const Allocator& alloc = Allocator() );				(8)	(since C++11)

Constructs a new container from a variety of data sources, optionally using a user supplied allocator alloc.

1) Default constructor. Constructs an empty container.

2) Constructs the container with count copies of elements with value value.

3) Constructs the container with count default-inserted instances of T. No copies are made.

4) Constructs the container with the contents of the range [first, last).

This constructor has the same effect as deque(static_cast<size_type>(first), static_cast<value_type>(last), a) if InputIt is an integral type.	(until C++11)
This overload only participates in overload resolution if InputIt satisfies InputIterator, to avoid ambiguity with the overload (2).	(since C++11)

5) Copy constructor. Constructs the container with the copy of the contents of other. If alloc is not provided, allocator is obtained as if by calling std::allocator_traits<allocator_type>::select_on_container_copy_construction(other.get_allocator()).

6) Move constructor. Constructs the container with the contents of other using move semantics. Allocator is obtained by move-construction from the allocator belonging to other.

7) Allocator-extended move constructor. Using alloc as the allocator for the new container, moving the contents from other; if alloc != other.get_allocator(), this results in an element-wise move.

8) Constructs the container with the contents of the initializer list init.

Parameters

alloc	-	allocator to use for all memory allocations of this container
count	-	the size of the container
value	-	the value to initialize elements of the container with
first, last	-	the range to copy the elements from
other	-	another container to be used as source to initialize the elements of the container with
init	-	initializer list to initialize the elements of the container with

Complexity

1) Constant

2-3) Linear in count

4) Linear in distance between first and last

5) Linear in size of other

6) Constant.

7) Linear if alloc != other.get_allocator(), otherwise constant.

8) Linear in size of init.

Notes

After container move construction (overload (6)), references, pointers, and iterators (other than the end iterator) to other remain valid, but refer to elements that are now in *this. The current standard makes this guarantee via the blanket statement in §23.2.1[container.requirements.general]/12, and a more direct guarantee is under consideration via LWG 2321.

Example

Run this code

#include <deque>
#include <string>
#include <iostream>
 
template<typename T>
std::ostream& operator<<(std::ostream& s, const std::deque<T>& v) {
    s.put('[');
    char comma[3] = {'\0', ' ', '\0'};
    for (const auto& e : v) {
        s << comma << e;
        comma[0] = ',';
    }
    return s << ']';
}
 
int main() 
{
    // c++11 initializer list syntax:
    std::deque<std::string> words1 {"the", "frogurt", "is", "also", "cursed"};
    std::cout << "words1: " << words1 << '\n';
 
    // words2 == words1
    std::deque<std::string> words2(words1.begin(), words1.end());
    std::cout << "words2: " << words2 << '\n';
 
    // words3 == words1
    std::deque<std::string> words3(words1);
    std::cout << "words3: " << words3 << '\n';
 
    // words4 is {"Mo", "Mo", "Mo", "Mo", "Mo"}
    std::deque<std::string> words4(5, "Mo");
    std::cout << "words4: " << words4 << '\n';
}

Output:

words1: [the, frogurt, is, also, cursed]
words2: [the, frogurt, is, also, cursed]
words3: [the, frogurt, is, also, cursed]
words4: [Mo, Mo, Mo, Mo, Mo]

See also

assign	assigns values to the container (public member function)
operator=	assigns values to the container (public member function)