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;
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;
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;
int arr2;
int arr3;
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