set_intersection.md

set_intersection()

Function

Constructs a sorted range beginning consisting of elements that are found in both sorted ranges [first1, last1) and [first2, last2).

If some element is found m times in [first1, last1) and n times in [first2, last2), the first x number of elements will be copied from the first range to the destination range where x is the minimum of m and n.

The order of equivalent elements is preserved.

The resulting range cannot overlap with either of the input ranges.

Declaration

set_intersection(first1,last1,first2,last2,result)

where, 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), which contains all the elements between first2 and last2, including the element pointed by first2 but not the element pointed by last2.

result: Output iterator to the initial position of the range where the resulting sequence is stored.

Return value: Returns an iterator past the end of the constructed range.

Example

#include <iostream>
#include <vector>
#include <algorithm> //set_intersection, sort
#include <iterator> //back_inserter
using namespace std;
int main()
{
    vector<int> v1{1,2,3,4,5,6,7,8};
    vector<int> v2{5,7,9,10};
    sort(v1.begin(), v1.end());
    sort(v2.begin(), v2.end());
    vector<int> v_intersection;
    set_intersection(v1.begin(), v1.end(),v2.begin(), v2.end(),back_inserter(v_intersection));
    for(int n : v_intersection) cout << n << ' ';
}

Output:

5 7