STL algorithm算法reverse,reverse_copy(50)

时间：2014-09-25 12:52:39 阅读：169 评论：0 收藏：0 [点我收藏+]

reverse原型：

<span style="font-size:18px;">std::reverse
template <class BidirectionalIterator>
  void reverse (BidirectionalIterator first, BidirectionalIterator last);</span>

反转范围内的元素。

行为类似于：

template <class BidirectionalIterator>
  void reverse (BidirectionalIterator first, BidirectionalIterator last)
{
  while ((first!=last)&&(first!=--last)) {
    std::iter_swap (first,last);
    ++first;
  }
}

reserve_copy原型：

std::reverse_copy

template <class BidirectionalIterator, class OutputIterator>
  OutputIterator reverse_copy (BidirectionalIterator first,
                               BidirectionalIterator last, OutputIterator result);

将范围内的元素以逆序的顺序存放到result开始的位置。

返回值为最后一个被覆盖元素的下一个位置的迭代器。

行为类似于：

template <class BidirectionalIterator, class OutputIterator>
  OutputIterator reverse_copy (BidirectionalIterator first,
                               BidirectionalIterator last, OutputIterator result)
{
  while (first!=last) {
    --last;
    *result = *last;
    ++result;
  }
  return result;
}

一个简单的例子：

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
void reversecopy()
{
    vector<int> vi{1,2,3,4,4,6};
    vector<int> vresult(6);
    cout<<"vi=";
    for(int i:vi)
        cout<<i<<" ";
    cout<<endl;
    cout<<"vreult=";
    for(int i:vresult)
        cout<<i<<" ";
    cout<<endl;

    reverse(vi.begin(),vi.end());
    cout<<"after reverse(vi.begin(),vi.end())"<<endl;
    cout<<"vi=";
    for(int i:vi)
        cout<<i<<" ";
    cout<<endl;
    reverse_copy(vi.begin(),vi.end(),vresult.begin());
    cout<<"after  reverse_copy(vi.begin(),vi.end(),vresult.begin());"<<endl;
    cout<<"vreult=";
    for(int i:vresult)
        cout<<i<<" ";
    cout<<endl;

}

运行截图：

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