STL deque的back方法（5）

原文地址：http://www.cplusplus.com/reference/deque/deque/back/

public member function

<deque>

std::deque::back

      reference back();
const_reference back() const;

Access last element

Returns a reference to the last element in the container.

返回容器最后一个元素的引用。

Unlike member deque::end, which returns an iterator just past this element, this function returns a direct reference.

和end不同，end是返回一个迭代器，该方法返回一个引用。

Calling this function on an empty container causes undefined behavior.

对一个空的容器调用该方法会导致为定义的行为。

例子：

#include <iostream>
#include <deque>
#include <vector>
using namespace std;
int main()
{
	deque<int> di{1,2,3,4,5};
	for(int i:di)
		cout<<i<<" ";
	cout<<endl;
	cout<<"di.back()="<<di.back()<<endl;
	
	deque<double> dd;
	cout<<"dd.back()="<<dd.back()<<endl;
	


}

运行截图：

Parameters

none

Return value

A reference to the last element in the deque container.

返回deque最后一个元素的引用。

If the deque object is const-qualified, the function returns a const_reference. Otherwise, it returns a reference.

Member types reference and const_reference are the reference types to the elements of the container (see deque member types).

Example

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

// deque::back #include <iostream> #include <deque> int main () { std::deque<int> mydeque; mydeque.push_back(10); while (mydeque.back() != 0) mydeque.push_back ( mydeque.back() -1 ); std::cout << "mydeque contains:"; for (std::deque<int>::iterator it = mydeque.begin(); it!=mydeque.end(); ++it) std::cout << ' ' << *it; std::cout << '\n'; return 0; }

Edit & Run

Output:

mydeque contains: 10 9 8 7 6 5 4 3 2 1 0

Complexity

Constant.

Iterator validity

No changes.

Data races

The container is accessed (neither the const nor the non-const versions modify the container).
The last element is potentially accessed or modified by the caller. Concurrently accessing or modifying other elements is safe.

Exception safety

If the container is not empty, the function never throws exceptions (no-throw guarantee).

Otherwise, it causes undefined behavior.

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//翻译的不好的地方请多多指导，可以在下面留言或者点击左上方邮件地址给我发邮件，指出我的错误以及不足，以便我修改，更好的分享给大家，谢谢。

//今后的翻译将以简洁为主，翻译其主要意思，不再每句翻译。

转载请注明出处：http://blog.csdn.net/qq844352155
author:天下无双

Email:[email protected]

2014-9-1

于GDUT

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