C program to find the union of two arrays

Given two integer arrays, we have to find the union using C program.

Program:

The source code to find the union of two arrays is given below. The given program is compiled and executed using GCC compile on UBUNTU 18.04 OS successfully.

// C program to find the union of two arrays

#include <stdio.h>

int findUnion(int arr1[], int arr2[], int arr3[])
{
    int i = 0;
    int j = 0;
    int k = 0;

    while ((i < 5) && (j < 5)) {
        if (arr1[i] < arr2[j]) {
            arr3[k] = arr1[i];
            i++;
            k++;
        }
        else if (arr1[i] > arr2[j]) {
            arr3[k] = arr2[j];

            j++;
            k++;
        }
        else {
            arr3[k] = arr1[i];
            i++;
            j++;
            k++;
        }
    }

    if (i == 5) {
        while (j < 5) {
            arr3[k] = arr2[j];
            j++;
            k++;
        }
    }
    else {
        while (i < 5) {
            arr3[k] = arr1[i];
            i++;
            k++;
        }
    }
    return k;
}

int main()
{
    int arr1[5] = { 1, 2, 3, 4, 5 };
    int arr2[5] = { 2, 3, 5, 7, 8 };
    int arr3[10] = { 0 };

    int len = 0;
    int cnt = 0;

    len = findUnion(arr1, arr2, arr3);

    printf("Union of arr1 and arr2 is: ");
    for (cnt = 0; cnt < len; cnt++)
        printf("%d ", arr3[cnt]);

    printf("\n");

    return 0;
}

Output:

Union of arr1 and arr2 is: 1 2 3 4 5 7 8

Explanation:

Here, we created two arrays arr1, arr2 with 5 integer elements. Then we find the union of both arrays using the findUnion() function and assign the result into the arr3 array. The findUnion() function is a user-defined function. After that, we printed the intersected elements on the console screen.