# How to intersect two arrays in Kotlin

# How to intersect two array elements in Kotlin :

The intersection is used to find out the common elements in two arrays. For example, if array *A* holds *1,2,3,4,5* and array *B* holds *2,5,6*, the intersection between *A* and *B* will be *2,5*.

In this tutorial, we will learn how to find out the intersection between two array elements.

## intersect function :

Arrays come with one inbuilt function called *intersect* that we can use to find out the intersection between one array and one iterable. This function can be defined as below :

infix fun Array.intersect( other: Iterable ): Set

As you can see that this method takes one *iterable* as a parameter and returns one *set* holding common elements of the array and the iterable. The set preserves the order of the elements as the original array.

## Example :

Let’s try to understand how *intersect* works with an example :

import java.util.* fun main(args: Array) { //1 val firstArray = arrayOf(1,2,3,4,5) val secondArray = arrayOf(2,5,6,7) //2 println(Arrays.toString(firstArray)) println(Arrays.toString(secondArray)) //3 val iArray = firstArray.intersect(secondArray.toList()).toIntArray() //4 println(Arrays.toString(iArray)) }

This program will print the below output :

[1, 2, 3, 4, 5] [2, 5, 6, 7] [2, 5]

### Explanation :

*The commented numbers in the above program denote the steps below :
*

1. First of all, create two arrays of integers

*firstArray*and

*secondArray*.

2. Print both arrays to the user.

3. Now, find out the intersection of these two arrays. As the return value is a

*set*, we need to convert it to an array using

*toIntArray()*. Also, this method takes only one

*iterable*as a parameter. So, we are converting the array to a list while passing it to

*intersect*.

4. The final result is stored in

*iArray*. Print the values of the array using

*Arrays.toString()*.

## Conclusion :

In this tutorial, we have learned how to use *intersect* function with an array to find out the intersection between two arrays in Kotlin. We can also use *intersect* with other iterables like a list, set, map etc. We will publish one new post with examples for other iterables. Try to run the example shown above and drop one comment below.

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