[deque.cons]

# 23 Containers library [[containers]](./#containers)

## 23.3 Sequence containers [[sequences]](sequences#deque.cons)

### 23.3.5 Class template deque [[deque]](deque#cons)

#### 23.3.5.2 Constructors, copy, and assignment [deque.cons]

[🔗](#lib:deque,constructor)

`constexpr explicit deque(const Allocator&);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6624)

*Effects*: Constructs an emptydeque,
using the specified allocator[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6630)

*Complexity*: Constant[.](#2.sentence-1)

[🔗](#lib:deque,constructor_)

`constexpr explicit deque(size_type n, const Allocator& = Allocator());
`

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6641)

*Preconditions*: T is *Cpp17DefaultInsertable* into deque[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6645)

*Effects*: Constructs a deque withn default-inserted elements using the specified allocator[.](#4.sentence-1)

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6650)

*Complexity*: Linear in n[.](#5.sentence-1)

[🔗](#lib:deque,constructor__)

`constexpr deque(size_type n, const T& value, const Allocator& = Allocator());
`

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6661)

*Preconditions*: T is *Cpp17CopyInsertable* into deque[.](#6.sentence-1)

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6665)

*Effects*: Constructs adeque with n copies of value,
using the specified allocator[.](#7.sentence-1)

[8](#8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6672)

*Complexity*: Linear in n[.](#8.sentence-1)

[🔗](#lib:deque,constructor___)

`template<class InputIterator>
  constexpr deque(InputIterator first, InputIterator last, const Allocator& = Allocator());
`

[9](#9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6684)

*Effects*: Constructs adeque equal to the range
[first, last),
using the specified allocator[.](#9.sentence-1)

[10](#10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6692)

*Complexity*: Linear in distance(first, last)[.](#10.sentence-1)

[🔗](#lib:deque,constructor____)

`template<[container-compatible-range](container.intro.reqmts#concept:container-compatible-range "23.2.2.1 Introduction [container.intro.reqmts]")<T> R>
  constexpr deque(from_range_t, R&& rg, const Allocator& = Allocator());
`

[11](#11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6704)

*Effects*: Constructs a deque with the elements of the range rg,
using the specified allocator[.](#11.sentence-1)

[12](#12)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/containers.tex#L6709)

*Complexity*: Linear in ranges​::​distance(rg)[.](#12.sentence-1)