STLarray的rend方法（17）

2016-02-24

字数统计: 708字 | 阅读时长≈ 3分

STLarray的rend方法（17）

原文地址：http://www.cplusplus.com/reference/array/array/rend/

public member function

std::array::rend

reverse_iterator rend() noexcept;
const_reverse_iterator rend() const noexcept;

Return reverse iterator to reverse end

Returns a reverse iterator pointing to the theoretical element preceding the first element in the array (which is considered its reverse end).

返回一个反向迭代器指向理论上存在于array容器第一个元素之前的元素。（这个元素被认为是反向的结尾）

//今天突然发现用反向代替翻转更好0.0

The range between array::rbegin and array::rend contains all the elements of the array (in reverse order).

范围rbegin和rend包括了array里面的所有元素（逆序）.

Parameters

none

Return Value

A reverse iterator to the reverse end of the sequence.

返回值是一个反向迭代器指向序列的反向结尾。

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

如果array对象是const,那么返回的是const迭代器。

Member types reverse_iterator and const_reverse_iterator are reverse random access iterator types (pointing to an element and to a const element, respectively). See vector member types.

迭代器类型属于随机访问迭代器。

Example

// array::rbegin/rend
#include <iostream>
#include <array>

int main ()
{
  std::array<int,4> myarray = {4, 26, 80, 14} ;

  std::cout << "myarray contains:";
  for ( auto rit=myarray.rbegin() ; rit < myarray.rend(); ++rit )
    std::cout << ' ' << *rit;

  std::cout << '\n';

  return 0;
}

Edit & Run

Output:

14 80 26 4

Notice how the reverse iterator iterates through the array in a reverse way by increasing the iterator.

注意反向迭代器递增的时候是翻转着移动的。

例子：

#include
#include
using namespace std;
int main()
{
array<int,5> ai{10,20,30,40,50};
auto it=ai.end();
cout<<”ai=”;
for(int i:ai)
cout<<i<<” “;
cout<<endl;
cout<<”ai.rend()=”<<*ai.rend()<<endl;
cout<<”ai.rend()-1=”<<*(ai.rend()-1)<<endl;
cout<<”ai.rend()-2=”<<*(ai.rend()-2)<<endl;
cout<<”ai.rend()-3=”<<*(ai.rend()-3)<<endl;

}

运行结果：

Complexity

Constant.

Iterator validity

No changes.

Data races

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.

容器元素不会被访问，但是返回的迭代器可以用来访问以及修改元素，同时访问以及修改他们都是安全的。