How to find common elements between two Arrays using STL in C++?
Last Updated :
26 Apr, 2019
Given two arrays, find common elements between these two arrays using STL in C++.
Example:
Input:
arr1[] = {1, 45, 54, 71, 76, 12},
arr2[] = {1, 7, 5, 4, 6, 12}
Output: {1, 12}
Input:
arr1[] = {1, 7, 5, 4, 6, 12},
arr2[] = {10, 12, 11}
Output: {1, 4, 12}
Approach: Common elements can be found with the help of set_intersection() function provided in STL.
Syntax:
set_intersection (InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result);
#include <bits/stdc++.h>
using namespace std;
int main()
{
int arr1[] = { 1, 45, 54, 71, 76, 12 };
int arr2[] = { 1, 7, 5, 4, 6, 12 };
int n1 = sizeof (arr1) / sizeof (arr1[0]);
int n2 = sizeof (arr2) / sizeof (arr2[0]);
sort(arr1, arr1 + n1);
sort(arr2, arr2 + n2);
cout << "First Array: " ;
for ( int i = 0; i < n1; i++)
cout << arr1[i] << " " ;
cout << endl;
cout << "Second Array: " ;
for ( int i = 0; i < n2; i++)
cout << arr2[i] << " " ;
cout << endl;
vector< int > v(n1 + n2);
vector< int >::iterator it, st;
it = set_intersection(arr1, arr1 + n1,
arr2, arr2 + n2,
v.begin());
cout << "\nCommon elements:\n" ;
for (st = v.begin(); st != it; ++st)
cout << *st << ", " ;
cout << '\n' ;
return 0;
}
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Output:
First Array: 1 12 45 54 71 76
Second Array: 1 4 5 6 7 12
Common elements:
1, 12,
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