check if an string exists in a list of strings, using powershell

Question

I have Powershell version 3,4 and 5 in my environment. When I write below code it continuously gave me false, though $CompatibleOS contains output of $OSversions.

   [string] $CompatibleOS = '2016','2012','2008'
   $OSVersion=[regex]::Matches(((Get-WmiObject -class Win32_OperatingSystem).caption), "([0-9]{4})")

   if ( $CompatibleOS -contains  $OSVersion)
   {
      return $TRUE
   }
   else
   {
      return $FALSE
   }

but when I changed above code to below, it worked. What could be the issue?

 [string] $CompatibleOS = '2016','2012','2008'
 $OSVersion=[regex]::Matches(((Get-WmiObject -class Win32_OperatingSystem).caption), "([0-9]{4})")

 if ( $CompatibleOS.contains($OSVersion))
 {
    return $TRUE
 }
 else
 {
      return $FALSE
 }

js2010 · Accepted Answer · 2023-07-28 14:52:13Z

40

This comes up a lot. -contains vs .contains(). They're very different. -contains has to match exactly. But the left side can be an array of strings. You actually joined everything into one string on the left with the [string] cast.

Note that .contains() is case sensitive. There's an option in powershell 7 to adjust that.

$compatibleos
'2016 2012 2008'

'2016 2012 2008' -contains '2016'
False

'2016 2012 2008'.contains('2016')
True

'2016','2012','2008' -contains '2016'
True

('2016','2012','2008').contains('2016')
True

'a'.contains('A')
False

'a'.contains('A','CurrentCultureIgnoreCase') # PS 7 only
True

edited Jul 28, 2023 at 14:52

answered Jul 8, 2019 at 12:32

js2010

28.3k6 gold badges82 silver badges88 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Daniel Morritt Over a year ago

Good explanation, OP's mistake was making the list a single string. OP can fix this really easily by either removing [string] (my preferred), or using [string[]] instead of [string].

guiwhatsthat · Accepted Answer · 2019-07-08 08:50:30Z

From the MS documentation

-Contains Description: Containment operator. Tells whether a collection of reference values includes a single test value. Always returns a Boolean value. Returns TRUE only when the test value exactly matches at least one of the reference values.

The important part is here is "only when the test value exactly matches". In your case you try to compare the string "2016 2012 2008" with as an example 2016, this doese't match exactly. In this case you should use the -like operator. Or you define your compatibleOS variable as an string array like that [String[]], then you can use the -contains.

Additonal, check whats inside the OSVersion variable. It is a machtcollection not a string. If you define your compatibleOS variable as a string array and you use $OSVersion.Value both of your examples will work.

chrki · Accepted Answer · 2024-11-08 11:59:54Z

4

Although the $CompatibleOS contains output of $OSversions, however the -contains is only used against a single test value, and return true when the test value exactly matches at least one of the reference values.

However, when the test value is a collection, the Contains operator uses reference equality. It returns TRUE only when one of the reference values is the same instance of the test value object. What is of importance is that they have to be of the same instance in this case.

For e.g.:

PS> "abc", "def", "ghi" -contains "abc", "def"

->False

PS> $a = "abc", "def"

PS> "abc", "def", "ghi" -contains $a

->False

PS> $a, "ghi" -contains $a

->True

Note, how the last one returns true due to the same instance, and the rest were false. Thus while using -contains, you received False. However when you use the contains(..) format, it does not check for the same instance and thus returned True, in your case.

edited Nov 8, 2024 at 11:59

chrki

6,3436 gold badges39 silver badges60 bronze badges

answered Jul 8, 2019 at 9:00

muditrustagii

8037 silver badges18 bronze badges

1 Comment

js2010 Over a year ago

$comparibleos is actually one string.

Rama Sharma · Accepted Answer · 2022-05-12 14:27:28Z

0

for me below syntax worked

ForEach ($content in $logFileContent) {
  
     if( $content.contains("MainClass")){
       echo  "MainClass: $content" >> $log
           }
         }

answered May 12, 2022 at 14:27

Rama Sharma

11611 bronze badges

1 Comment

André Pletschette Over a year ago

You should add to your comment what is contained in $logFileContent

Ravi Yadav G · Accepted Answer · 2023-06-02 06:15:12Z

-2

$datepoint = "MAIN_20230601" $accountingTypesArray = "AccruedExternalInterest","AccruedInternalInterest","AccruedFee","BookedExternalInterest","BookedInternalInterest","BookedFee" foreach ($item in $accountingTypesArray) { $finalUrl = "https://encx-eodd-syst.danskenet.net/api/Delivery/Trigger?accountingPoint="+$datepoint+"&productSystem=WSO&accountingType="+$item $response = Invoke-RestMethod $finalUrl -Method 'GET' Write-Output $response.slideshow }

answered Jun 2, 2023 at 6:15

Ravi Yadav G

371 bronze badge

1 Comment

ryanwebjackson Over a year ago

Please explain this code solution.

Collectives™ on Stack Overflow

check if an string exists in a list of strings, using powershell

5 Answers 5

1 Comment

Comments

1 Comment

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

1 Comment

Comments

1 Comment

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related