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C program to find the intersection of two arrays

Here, we are going to learn how to find the intersection of two arrays in C programming language?
Submitted by Nidhi, on July 12, 2021

Problem statement

Here, we will create two integer arrays and find the intersection of both arrays and print the result on the console screen.

Finding intersection of two arrays

The source code to find the intersection 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 intersection of two arrays

// C program to find the Intersection of two arrays

#include <stdio.h>

int intersection(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]) {
            i++;
        }
        else if (arr1[i] > arr2[j]) {
            j++;
        }
        else {
            arr3[k] = arr1[i];
            i++;
            j++;
            k++;
        }
    }

    return k;
}

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

    int len = 0;
    int cnt = 0;

    len = intersection(arr1, arr2, arr3);

    printf("Intersection is: ");
    for (cnt = 0; cnt < len; cnt++)
        printf("%d ", arr3[cnt]);

    printf("\n");

    return 0;
}

Output

Intersection is: 2 3 5

Explanation

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

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