Compare Objects with PowerShell (Step by Step Guide)

The “Compare-Object” cmdlet helps to compare the contents of two files, strings, variables, or objects. It accepts two parameters, one is a reference set or file, while the other is a difference. Its major role is to produce or display the items list missing from the reference file. Objects usually are compared to find out the difference between them.

The following blog will cover methods to compare objects in PowerShell.

How to Compare Objects With PowerShell Using the “Compare-Object” Cmdlet?

The cmdlet “Compare-Object” in PowerShell compares the objects from the two corresponding files, folders, or arrays. It takes two parameters, “-ReferenceObject” and “-DifferenceObject”. The former parameter references the file, and the latter parameter differentiates the objects from a file.

These are the indicators that are displayed after the comparison of the objects:

Indicator	Description
==	Confirms that the content is present in both files.
=>	Confirms that content is present only in the “-DifferenceObject” file.
<=	Confirms that content is present only in the “-ReferenceObject” file.

Example 1: Compare the Objects Within a File

This example will compare the objects within a file using the “Compare-Object” cmdlet:

$Ref_File = Get-Content C:\\Doc\\Doc.txt
$Dif_File = Get-Content C:\\Doc\\File.txt
Compare-Object -ReferenceObject $Ref_file -DifferenceObject $Dif_File -IncludeEqual

According to the above code:

First, initialize the two variables “$Ref_File” and “$Dif_File”.
Assign each of them the “Get-Content” cmdlet to retrieve the data within the given files and specify the path of the two text files.
Lastly, to compare the files, first, invoke the “Compare-Object” cmdlet, then add the “-ReferenceObject”, and assign the reference file assigned variable, which is “$Ref-File”.
After that, add another parameter, “-DifferenceObject”, and assign the difference file assigned variable “$Dif-File”.
At the end, add the “-IncludeEqual” flag to display the matching objects from the referenced file:

Example 2: Compare Files in the Folders

This example will compare the file within two folders using PowerShell “Compare-Object” command:

$Ref_Fold = Get-ChildItem C:\\Doc\\Folder_1\\
$Dif_Fold = Get-ChildItem C:\\Doc\\Folder_2\\
Compare-Object $Ref_Fold $Dif_Fold -IncludeEqual

In the above code, the “Get-ChildItem” cmdlet is utilized to retrieve the files from specified folder locations:

Example 3: Compare Two Arrays Using the “Compare-Object” cmdlet

This example will compare objects of two arrays:

$array_1 = @("Cat", "Dog", "Hen")
$array_2 = @("Dog", "Hen", "Horse")
Compare-Object $array_1 $array_2 -IncludeEqual

According to the above code:

First, initialize two variables and assign both of the arrays with objects.
After that, compare both using the “Compare-Object” cmdlet:

Now, evaluate the difference using the description of the side indicators.

Conclusion

The objects in PowerShell are compared using the “Compare-Object” cmdlet. This cmdlet uses the parameters “-ReferenceObject” and “-DifferenceObject”. The former parameter references the file, and the latter parameter differentiates the objects from a file. This write-up has elaborated on the methods to compare files in PowerShell.