C++ Program to find union and intersection of two arrays


In this program, You will learn how to find union and intersection of two arrays in C++.


First list is: 1 2 3 4 5

Second list is: 3 4 5

Union is: 1 2 3 4 5

Intersection is: 3 4 5


Example: How to find union and intersection of two arrays in C++

Run it Now
#include<iostream>
using namespace std;

void printUnion(int arr1[], int arr2[], int len1, int len2) {

    int f, i, j, k = 0;
    int arr3[100];
    for (i = 0; i < len1; i++) {
        arr3[k] = arr1[i];
        k++;
    }

    for (i = 0; i < len2; i++) {
        f = 0;
        for (j = 0; j < len1; j++) {
            if (arr2[i] == arr1[j]) {
                f = 1;
            }
        }
        if (f == 0) {
            arr3[k] = arr2[i];
            k++;
        }
    }
    cout << "\nUnion of Two Array is :";
    for (i = 0; i < k; i++) {
        cout << arr3[i] << " ";
    }
}

void printIntersection(int arr1[], int arr2[], int len1, int len2) {

    int arr3[100];
    int i, j, k = 0;

    for (i = 0; i < len1; i++) {
        for (j = 0; j < len2; j++) {
            if (arr1[i] == arr2[j]) {
                arr3[k] = arr1[i];
                k++;
            }
        }
    }
    cout << "\nIntersection of Two Array is :";
    for (i = 0; i < k; i++) {
        cout << arr3[i] << " ";
    }
}

int main() {

    int arr1[100];
    int arr2[100];
    int arr3[100];
    int i, j, len1, len2;

    cout << "Enter Size of 1st Array :";
    cin>>len1;

    cout << "\nEnter 1st Array Elements :";
    for (i = 0; i < len1; i++) {
        cin >> arr1[i];
    }
    cout << "\nEnter Size of 2nd Array :";
    cin>>len2;

    cout << "\nEnter 2nd Array Elements :";
    for (i = 0; i < len2; i++) {
        cin >> arr2[i];
    }

    printUnion(arr1, arr2, len1, len2);
    printIntersection(arr1, arr2, len1, len2);

    return 0;
}

Output:

Enter Size of 1st Array :5
Enter 1st Array Elements :1 2 3 4 5
Enter Size of 2nd Array :3
Enter 2nd Array Elements :3 4 5
Union of Two Array is :1 2 3 4 5
Intersection of Two Array is :3 4 5