交集

• OutputIterator set_intersection (
  InputIterator1 first1, InputIterator1 last1,
  InputIterator2 first2, InputIterator2 last2,
  OutputIterator result)
• 返回值是交集最后一个元素的下个元素的迭代器

例子：

#include "stdafx.h"
#include <iostream>
#include <algorithm>
#include <vector>
#include <time.h>
#include <numeric>
using namespace std;


void Print(int n)
{
	cout << " " << n;
}


int main()
{
	vector<int> v1;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	cout << "v1 : ";
	for_each(v1.begin(),v1.end(), Print); cout << endl;

	vector<int> v2;
	for (int i = 5; i < 20; i++)
	{
		v2.push_back(i);
	}
	cout << "v2 : ";
	for_each(v2.begin(), v2.end(), Print); cout << endl;![在这里插入图片描述](https://img-blog.csdn.net/20181012162344674?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3p6eWN6enlj/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70)

	vector<int> v3;
	v3.resize(min(v1.size(), v2.size()));

    vector<int>::iterator it=set_intersection(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin());
	

	cout << "交集v3 : ";
	for_each(v3.begin(), it, Print); cout << endl;

    return 0;
}

结果：

并集

• OutputIterator set_union (
  InputIterator1 first1, InputIterator1 last1,
  InputIterator2 first2, InputIterator2 last2,
  OutputIterator result )

• 返回值：并集最后一个元素的  下一个元素的迭代器

#include "stdafx.h"
#include <iostream>
#include <algorithm>
#include <vector>
#include <time.h>
#include <numeric>
using namespace std;


void Print(int n)
{
	cout << " " << n;
}


int main()
{
	vector<int> v1;
	for (int i = 0; i < 7; i++)
	{
		v1.push_back(i);
	}
	cout << "v1 : ";
	for_each(v1.begin(),v1.end(), Print); cout << endl;



	vector<int> v2;
	for (int i = 5; i < 10; i++)
	{
		v2.push_back(i);
	}
	cout << "v2 : ";
	for_each(v2.begin(), v2.end(), Print); cout << endl;



	vector<int> v3;
	v3.resize(v1.size()+v2.size());
    vector<int>::iterator it=set_union(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin());
	

	cout << "交集v3 : ";
	for_each(v3.begin(), it, Print); cout << endl;

    return 0;
}

结果：

差集：v1-(v1和v2的交集)

• OutputIterator set_difference (
  InputIterator1 first1, InputIterator1 last1,
  InputIterator2 first2, InputIterator2 last2,
  OutputIterator result)

• 返回值：差集最后一个元素的   下一个元素的迭代器

#include "stdafx.h"
#include <iostream>
#include <algorithm>
#include <vector>
#include <time.h>
#include <numeric>
using namespace std;


void Print(int n)
{
	cout << " " << n;
}


int main()
{
	vector<int> v1;
	for (int i = 0; i < 7; i++)
	{
		v1.push_back(i);
	}
	cout << "v1 : ";
	for_each(v1.begin(),v1.end(), Print); cout << endl;



	vector<int> v2;
	for (int i = 5; i < 10; i++)
	{
		v2.push_back(i);
	}
	cout << "v2 : ";
	for_each(v2.begin(), v2.end(), Print); cout << endl;



	vector<int> v3;
	v3.resize(v1.size());
    vector<int>::iterator it= set_difference(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin());
	

	cout << "差集 v3 : ";
	for_each(v3.begin(), it, Print); cout << endl;

    return 0;
}

结果：