PowerShell Contains Operator

Migel Hewage Nimesha Dec 06, 2021
PowerShell Contains Operator

There are different operators available in the PowerShell that can filter/compare or find elements that match a specified input string. The -contains is one of the major comparison operators, classified as a Containment type operator.

There are four main containment type operators.

  • -contains
  • -notcontains
  • -in
  • -notin

In this article, we are only focusing on the -contains operator. This operator always returns a Boolean value (true/false) if there is a match. Also, the performance-wise, -contains operator is pretty fast to return the results because it stops comparing the input as soon as it finds the first match.

the -contains Operator in PowerShell

This operator can be used to check whether a collection contains a specific element. Its syntax is as below.

[set / collection] -contains [test-value or test-object]

[set/collection] can be a set of string values (comma separated), for example, "Hello" or "FOX", "2ndLane".

[test-value or test-object] can be an element or set of elements (collection), for example, "Hello" or "Hello", "FOX", "No2".

Check for a Certain Element

  • Example 01:
"Hello", "FOX", "2ndLane" -contains "2ndLane"



The input element/value is "2ndLane" and it can be located in the left-hand side collection/set. Therefore, the output/result is obviously True.

  • Example 02:
"Hello", "FOX", "2ndLane" -contains "NotInTheCollection"



The input element/value is "NotInTheCollection" and it is not included in the right-hand side collection. Therefore, the above command was evaluated to False.

The important fact about the -contains operator is that it checks for the exact input element within the given collection/set. The command will be evaluated as False when a portion/substring has been given as the input element.

  • Example 03:
"Hello", "FOX", "FullStringGiven" -contains "StringGiven"



In the above example, the input element is the "StringGiven", but it is a substring of the "FullStringGiven" element of the right-hand side collection. Therefore, the input element doesn’t match an exact element from the right-hand side collection, and the result is False as expected.

Check for a Set of Elements/Collection With the -contains Operator in PowerShell

One of the biggest advantages of the -contains operator is that it can be used to find whether the given collection/set matches an input collection. It is important to keep in mind that the operator checks whether the same instances exist on the left-hand side (given collection) and the right-hand side (input collection/test-collection). That means these containment operators use reference equality when the input object (test-object) is a collection.

Example 01

$leftsideobj = "Hello", "NewString1"

Here, we assign the $leftsideobj variable to the set of elements (collection).

$leftsideobj, "AnotherString" -contains $leftsideobj

Then, we use -contains operator to find a match.



This command has been evaluated to True. Because the input collection is $leftsideobj and the same instance is available in the left-hand side collection. It means the reference equality has been fulfilled. Therefore, the result is True.

Example 02

$newleftsideobj = "Hello", "Test"

Here, we got the $newleftsideobj variable assigned to a collection that contains "Hello" and "Test" elements.

`"Hello", "Test", "NewString1" -contains $newleftsideobj`



The above command was evaluated to False. You can see that the input collection (right-hand side) is $newleftsideobj, which indirectly the two elements "Hello" and "Test". If you notice the left-hand side, we got "Hello" and "Test" elements available. But it doesn’t satisfy the reference equality. That is why the output is False.

Migel Hewage Nimesha avatar Migel Hewage Nimesha avatar

Nimesha is a Full-stack Software Engineer for more than five years, he loves technology, as technology has the power to solve our many problems within just a minute. He have been contributing to various projects over the last 5+ years and working with almost all the so-called 03 tiers(DB, M-Tier, and Client). Recently, he has started working with DevOps technologies such as Azure administration, Kubernetes, Terraform automation, and Bash scripting as well.

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