std::deque

Defined in header <deque>
template< class T, class Allocator = std::allocator<T> > class deque;	(1)
namespace pmr { template <class T> using deque = std::deque<T, std::pmr::polymorphic_allocator<T>>; }	(2)	(since C++17)

std::deque%28双结束队列%29是一个索引序列容器，它允许在开始和结束时快速插入和删除。此外，在deque的两端插入和删除不会使指针或对其余元素的引用无效。

相对于std::vector，deque的元素不是连续存储的：典型实现使用一系列单独分配的固定大小数组，并附加簿记，这意味着索引访问std：deque必须执行两个指针取消，而向量%27s索引访问只执行一个。

根据需要，自动扩展和收缩DEQE的存储。扩展一个设备比扩展一个std::vector因为它不涉及将现有元素复制到新的内存位置。另一方面，deques通常具有很大的最小内存开销；一个只包含一个元素的deque必须分配其完整的内部数组%28e.g。64位libstdc++上的对象大小是对象大小的8倍；64位libc++%29上的对象大小是对象大小的16倍或4096字节，以较大者为准。

对deques的常见操作的复杂性%28---效率%---29如下：

随机存取-常数O%281%29

在结尾或开头插入或删除元素-常数O%281%29

元素的插入或去除.线性O%28N%29

std::deque满足…的要求Container，，，AllocatorAwareContainer，，，SequenceContainer和ReversibleContainer...

模板参数

T	-	The type of the elements. T must meet the requirements of CopyAssignable and CopyConstructible. (until C++11) The requirements that are imposed on the elements depend on the actual operations performed on the container. Generally, it is required that element type is a complete type and meets the requirements of Erasable, but many member functions impose stricter requirements. (since C++11)
T must meet the requirements of CopyAssignable and CopyConstructible.	(until C++11)
The requirements that are imposed on the elements depend on the actual operations performed on the container. Generally, it is required that element type is a complete type and meets the requirements of Erasable, but many member functions impose stricter requirements.	(since C++11)
Allocator	-	An allocator that is used to acquire/release memory and to construct/destroy the elements in that memory. The type must meet the requirements of Allocator. The behavior is undefined if Allocator::value_type is not the same as T.

迭代器失效

本节中仍有一些不准确之处，请参阅个别成员函数页以获得更多细节。

Operations	Invalidated
All read only operations	Never
swap, std::swap	The past-the-end iterator may be invalidated (implementation defined)
shrink_to_fit, clear, insert, emplace, push_front, push_back, emplace_front, emplace_back	Always
erase	If erasing at begin - only erased elements If erasing at end - only erased elements and the past-the-end iterator Otherwise - all iterators are invalidated (including the past-the-end iterator).
resize	If the new size is smaller than the old one : only erased elements and the past-the-end iterator If the new size is bigger than the old one : all iterators are invalidated Otherwise - none iterators are invalidated.
pop_front	Only to the element erased
pop_back	Only to the element erased and the past-the-end iterator

失效笔记

在deque的两端插入时，引用不会被insert和emplace...

push_front，，，push_back，，，emplace_front和emplace_back不要使任何对deque元素的引用无效。

当在deque的两端擦除时，对非擦除元素的引用不会被erase，，，pop_front和pop_back...

打电话给resize使用较小的大小，不会使任何对非擦除元素的引用失效。

打电话给resize使用更大的大小不会使对deque元素的引用无效。

成员类型

Member type	Definition
value_type	T
allocator_type	Allocator
size_type	Unsigned integer type (usually std::size_t)
difference_type	Signed integer type (usually std::ptrdiff_t)
reference	Allocator::reference (until C++11) value_type& (since C++11)	Allocator::reference	(until C++11)	value_type&	(since C++11)
Allocator::reference	(until C++11)
value_type&	(since C++11)
const_reference	Allocator::const_reference (until C++11) const value_type& (since C++11)	Allocator::const_reference	(until C++11)	const value_type&	(since C++11)
Allocator::const_reference	(until C++11)
const value_type&	(since C++11)
pointer	Allocator::pointer (until C++11) std::allocator_traits<Allocator>::pointer (since C++11)	Allocator::pointer	(until C++11)	std::allocator_traits<Allocator>::pointer	(since C++11)
Allocator::pointer	(until C++11)
std::allocator_traits<Allocator>::pointer	(since C++11)
const_pointer	Allocator::const_pointer (until C++11) std::allocator_traits<Allocator>::const_pointer (since C++11)	Allocator::const_pointer	(until C++11)	std::allocator_traits<Allocator>::const_pointer	(since C++11)
Allocator::const_pointer	(until C++11)
std::allocator_traits<Allocator>::const_pointer	(since C++11)
iterator	RandomAccessIterator
const_iterator	Constant random access iterator
reverse_iterator	std::reverse_iterator<iterator>
const_reverse_iterator	std::reverse_iterator<const_iterator>

成员函数

(constructor)	constructs the deque (public member function)
(destructor)	destructs the deque (public member function)
operator=	assigns values to the container (public member function)
assign	assigns values to the container (public member function)
get_allocator	returns the associated allocator (public member function)

元素存取

在访问指定元素时，使用边界检查%28公共成员函数%29

操作者。[]访问指定元素%28公共成员函数%29

前端访问第一个元素%28公共成员函数%29

返回访问最后一个元素%28公共成员函数%29

迭代器

BEGINCBEGIN将迭代器返回到开头%28的公共成员函数%29

End cend将迭代器返回到End%28公共成员函数%29

将反向迭代器返回到开头%28的公共成员函数%29

rend crend将反向迭代器返回到End%28公共成员函数%29

容量

空检查容器是否为空%28公共成员函数%29

Size返回元素数%28公共成员函数%29

马克斯[医]Size返回元素的最大可能数%28公共成员函数%29

收缩[医]到[医]FIT%28C++11%29通过释放未使用内存%28公共成员函数%29来减少内存使用

修饰符

清除内容%28公共成员功能%29

插入元素%28公共成员函数%29

嵌入%28C++11%29构造元素就地%28公共成员函数%29

擦除元素%28公共成员函数%29

推[医]向末尾%28公共成员函数%29添加一个元素

座落[医]Back%28C++11%29在%28公共成员函数%29的末尾构造一个就地元素。

波普[医]回移除最后一个元素%28公共成员函数%29

推[医]前端插入元素到开头%28公共成员函数%29

座落[医]前端%28c++11%29在开始处构造一个元素(%28公共成员函数%29)。

波普[医]前端移除第一个元素%28公共成员函数%29

调整大小更改存储的元素数%28公共成员函数%29

交换交换内容%28公共成员函数%29

非会员职能

operator==operator!=operator<operator<=operator>operator>=	lexicographically compares the values in the deque (function template)
std::swap(std::deque)	specializes the std::swap algorithm (function template)

例

二次

#include <iostream>
#include <deque>
 
int main()
{
    // Create a deque containing integers
    std::deque<int> d = {7, 5, 16, 8};
 
    // Add an integer to the beginning and end of the deque
    d.push_front(13);
    d.push_back(25);
 
    // Iterate and print values of deque
    for(int n : d) {
        std::cout << n << '\n';
    }
}

二次

产出：

二次

二次

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最后更新于：2017-12-18