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STL algorithm算法includes(23)

includes原型:

std::includes

template <class InputIterator1, class InputIterator2>
  bool includes ( InputIterator1 first1, InputIterator1 last1,
                  InputIterator2 first2, InputIterator2 last2 );

template <class InputIterator1, class InputIterator2, class Compare>
  bool includes ( InputIterator1 first1, InputIterator1 last1,
                  InputIterator2 first2, InputIterator2 last2, Compare comp );

该函数是测试  [first1,last1)里面是否包含了[first2,last2)里面的所有元素。

也就是说,后面那一个区间是否是前一个区间的子集。

[first1,last1)和[first2,last2)里面的元素应该先排好序,并且是使用同一规则排序。

其行为类似如下:

2
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11
template <class InputIterator1, class InputIterator2>
  bool includes (InputIterator1 first1, InputIterator1 last1,
                 InputIterator2 first2, InputIterator2 last2)
{
  while (first2!=last2) {
    if ( (first1==last1) || (*first2<*first1) ) return false;
    if (!(*first1<*first2)) ++first2;
    ++first1;
  }
  return true;
}
 
一个简单的例子:

#include <iostream>
#include <vector>
#include <array>
#include <algorithm>
using namespace std;
void includes2(){
    vector<int> vi{1,5,8,19,78,100,56};
    array<int,3> ai{19,100,56};
    vector<int> v2{5,11,20};
    sort(vi.begin(),vi.end());
    sort(ai.begin(),ai.end());
    sort(v2.begin(),v2.end());


    cout<<"at first,vi=";
    for_each(vi.begin(),vi.end(),[](int i){cout<<i<<" ";});
    cout<<endl;

    cout<<"at first,ai=";
    for_each(ai.begin(),ai.end(),[](int i){cout<<i<<" ";});
    cout<<endl;

    cout<<"at first,v2=";
    for_each(v2.begin(),v2.end(),[](int i){cout<<i<<" ";});
    cout<<endl;

    if(includes(vi.begin(),vi.end(),ai.begin(),ai.end()))
       cout<<"includes(vi.begin(),vi.end(),ai.begin(),ai.end())  return true!"<<endl;
    else
        cout<<"includes(vi.begin(),vi.end(),ai.begin(),ai.end())  return false!"<<endl;

    if(includes(vi.begin(),vi.end(),v2.begin(),v2.end()))
        cout<<"includes(vi.begin(),vi.end(),v2.begin(),v2.end()) return true!"<<endl;
    else
        cout<<"includes(vi.begin(),vi.end(),v2.begin(),v2.end()) return false!"<<endl;







}

运行截图:


如果不排序,则有会发生错误!

例如下面的例子:

#include <iostream>
#include <vector>
#include <array>
#include <algorithm>
using namespace std;
void includes2(){
    vector<int> vi{1,5,8,19,78,100,56};
    array<int,4> ai{19,100,56,1};
    vector<int> v2{5,11,20};
   // sort(vi.begin(),vi.end());
   // sort(ai.begin(),ai.end());
   // sort(v2.begin(),v2.end());


    cout<<"at first,vi=";
    for_each(vi.begin(),vi.end(),[](int i){cout<<i<<" ";});
    cout<<endl;

    cout<<"at first,ai=";
    for_each(ai.begin(),ai.end(),[](int i){cout<<i<<" ";});
    cout<<endl;

    cout<<"at first,v2=";
    for_each(v2.begin(),v2.end(),[](int i){cout<<i<<" ";});
    cout<<endl;

    if(includes(vi.begin(),vi.end(),ai.begin(),ai.end()))
       cout<<"includes(vi.begin(),vi.end(),ai.begin(),ai.end())  return true!"<<endl;
    else
        cout<<"includes(vi.begin(),vi.end(),ai.begin(),ai.end())  return false!"<<endl;

    if(includes(vi.begin(),vi.end(),v2.begin(),v2.end()))
        cout<<"includes(vi.begin(),vi.end(),v2.begin(),v2.end()) return true!"<<endl;
    else
        cout<<"includes(vi.begin(),vi.end(),v2.begin(),v2.end()) return false!"<<endl;







}

运行截图:




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//写的错误或者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。

转载请注明出处:http://blog.csdn.net/qq844352155

author:天下无双

Email:coderguang@gmail.com

2014-9-16

于GDUT

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STL algorithm算法includes(23)