STL deque的begin方法（6）

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

public member function

<deque>

std::deque::begin

• C++98
• C++11

      iterator begin() noexcept;
const_iterator begin() const noexcept;

Return iterator to beginning

Returns an iterator pointing to the first element in the deque container.

返回指向deque容器第一个元素的迭代器。

Notice that, unlike member deque::front, which returns a reference to the first element, this function returns a random access iteratorpointing to it.

If the container is empty, the returned iterator value shall not be dereferenced.

如果容器是空的，那么不应该对该方法返回的迭代器解除引用。

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.begin()="<<*di.begin()<<endl;
	
	deque<double> dd;
	cout<<"dd.begin()="<<*dd.begin()<<endl;
	


}

运行截图：

Parameters

none

Return Value

An iterator to the beginning of the sequence container.

返回一个指向序列开头的迭代器。

If the deque object is const-qualified, the function returns a const_iterator. Otherwise, it returns an iterator.

Member types iterator and const_iterator are random access iterator types (pointing to an element and to a const element, respectively).

Example

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

// deque::begin #include <iostream> #include <deque> int main () { std::deque<int> mydeque; for (int i=1; i<=5; i++) mydeque.push_back(i); std::cout << "mydeque contains:"; std::deque<int>::iterator it = mydeque.begin(); while (it != mydeque.end()) std::cout << ' ' << *it++; std::cout << '\n'; return 0; }

Edit & Run

Output:

mydeque contains: 1 2 3 4 5

Complexity

Constant.

Iterator validity

No changes.

Data races

The container is accessed (neither the const nor the non-const versions modify the container).
No contained elements are accessed by the call, but the iterator returned can be used to access or modify elements. Concurrently accessing or modifying different elements is safe.

Exception safety

No-throw guarantee: this member function never throws exceptions.

The copy construction or assignment of the returned iterator is also guaranteed to never throw.

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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，一些重复率太高的也将不再翻译，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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