兩組的交集僅由兩組中都存在的元素形成。函數複製的元素始終以相同的順序來自第一個範圍。兩個範圍內的元素都應已排序。
例子：
Input: 5 10 15 20 25 50 40 30 20 10 Output: The intersection has 2 elements: 10 20
1.使用“ <”比較元素：語法：
Template:
OutputIterator set_intersection (InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result);
參數：
first1, last1
Input iterators to the initial and final positions of the first
sorted sequence. The range used is [first1, last1), which contains
all the elements between first1 and last1, including the element
pointed by first1 but not the element pointed by last1.
first2, last2
Input iterators to the initial and final positions of the second
sorted sequence. The range used is [first2, last2).
result
Output iterator to the initial position of the range where the
resulting sequence is stored.
The pointed type shall support being assigned the value of an
element from the first range.
返回類型：
An iterator to the end of the constructed range.
// CPP program to illustrate
// std::set_intersection
#include <bits/stdc++.h>
int main()
{
int first[] = { 5, 10, 15, 20, 25 };
int second[] = { 50, 40, 30, 20, 10 };
int n = sizeof(first) / sizeof(first[0]);
std::vector<int> v1(5);
std::vector<int> v2(5);
std::vector<int>::iterator it, ls;
std::sort(first, first + 5);
std::sort(second, second + 5);
// Print elements
std::cout << "First array:";
for (int i = 0; i < n; i++)
std::cout << " " << first[i];
std::cout << "\n";
// Print elements
std::cout << "Second array:";
for (int i = 0; i < n; i++)
std::cout << " " << second[i];
std::cout << "\n\n";
// std::set_intersection
ls = std::set_intersection(first, first + 5, second, second + 5, v1.begin());
std::cout << "The intersection has " << (ls - v1.begin()) << " elements:";
for (it = v1.begin(); it != ls; ++it)
std::cout << ' ' << *it;
std::cout << "\n";
return 0;
}輸出：
First array:5 10 15 20 25 Second array:10 20 30 40 50 The intersection has 2 elements:10 20
2.通過使用預定義函數進行比較：語法：
Template:
OutputIterator set_intersection (InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result, Compare comp);
參數：
first1, last1, first2, last2, result are same as mentioned above.
comp
Binary function that accepts two arguments of the types pointed
by the input iterators, and returns a value convertible to bool.
The function shall not modify any of its arguments.
This can either be a function pointer or a function object.
It follows the strict weak ordering to order the elements.
返回類型：
An iterator to the end of the constructed range.
// CPP program to illustrate
// std::set_intersection
#include <bits/stdc++.h>
bool comp(int a, int b)
{
return a < b;
}
int main()
{
int first[] = { 5, 10, 15, 20, 25 };
int second[] = { 50, 40, 30, 20, 10 };
int n = sizeof(first) / sizeof(first[0]);
std::vector<int> v1(5);
std::vector<int> v2(5);
std::vector<int>::iterator it, ls;
std::sort(first, first + 5);
std::sort(second, second + 5);
// Print elements
std::cout << "First array:";
for (int i = 0; i < n; i++)
std::cout << " " << first[i];
std::cout << "\n";
// Print elements
std::cout << "Second array:";
for (int i = 0; i < n; i++)
std::cout << " " << second[i];
std::cout << "\n\n";
// std::set_intersection
ls = std::set_intersection(first, first + 5, second, second + 5, v1.begin(), comp);
std::cout << "The intersection has " << (ls - v1.begin()) << " elements:";
for (it = v1.begin(); it != ls; ++it)
std::cout << ' ' << *it;
std::cout << "\n";
return 0;
}輸出：
First array:5 10 15 20 25 Second array:10 20 30 40 50 The intersection has 2 elements:10 20
可能的應用：用於查找僅在兩個集合中都存在的元素。
1.可用於查找兩個班級中存在的學生列表。
// CPP program to demonstrate use of
// std::set_intersection
#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
using namespace std;
// Driver code
int main()
{
string first[] = { "Sachin", "Rakesh", "Sandeep", "Serena" };
string second[] = { "Vaibhav", "Sandeep", "Rakesh", "Neha" };
int n = sizeof(first) / sizeof(first[0]);
// Print students of first list
cout << "Students in first class:";
for (int i = 0; i < n; i++)
cout << " " << first[i];
cout << "\n";
// Print students of second list
cout << "Students in second class:";
for (int i = 0; i < n; i++)
cout << " " << second[i];
cout << "\n\n";
vector<string> v(10);
vector<string>::iterator it, st;
// Sorting both the list
sort(first, first + n);
sort(second, second + n);
// Using default operator<
it = set_intersection(first, first + n, second, second + n, v.begin());
cout << "Students attending both the classes only are:\n";
for (st = v.begin(); st != it; ++st)
cout << ' ' << *st;
cout << '\n';
return 0;
}輸出：
Students in first class:Sachin Rakesh Sandeep Serena Students in second class:Vaibhav Sandeep Rakesh Neha Students attending both classes only are: Rakesh Sandeep
相關用法
注：本文由純淨天空篩選整理自 std::set_intersection in C++。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。