You can use the following methods in PowerShell to find either the **union** or **intersection** of two arrays:

**Method 1: Find Union of Two Arrays**

**$first_array + $second_array | Select -Unique
**

This particular example will return the **union** of the arrays named **$first_array** and **$second_array**, which represents all of the unique values that belong to either array.

**Method 2: Find Intersection of Two Arrays**

**$first_array | Where {$second_array -contains $_}
**

This particular example will return the **intersection **of the arrays named **$first_array** and **$second_array**, which represents all of the unique values that belong in both arrays.

The following examples shows how to use each of these methods in practice.

**Example 1: Find Union of Two Arrays in PowerShell**

We can use the following syntax to define two arrays, **array1** and **array2**, and then find the **union** of those two arrays:

**$first_array = @(1, 2, 3, 4, 5)
$second_array = @(3, 4, 5, 6, 7)
$first_array + $second_array | Select -Unique
**

The following screenshot shows how to use this syntax in practice:

We can see that this returns all unique values that belong to either **$first_array **or **$second_array**:

**1, 2, 3, 4, 5, 6, 7**

**Example 2: Find Intersection of Two Arrays in PowerShell**

We can use the following syntax to define two arrays, **array1** and **array2**, and then find the **intersection **of those two arrays:

**$first_array = @(1, 2, 3, 4, 5)
$second_array = @(3, 4, 5, 6, 7)
$first_array | Where {$second_array -contains $_}
**

The following screenshot shows how to use this syntax in practice:

We can see that this returns all unique values that belong to both **$first_array **and **$second_array**:

**3, 4, 5**

**Related Tutorials**

The following tutorials explain how to perform other common tasks in PowerShell:

PowerShell: How to Compare Two Arrays

PowerShell: How to Remove Duplicate Values from Array

PowerShell: Check if String Exists in List of Strings