PowerShell -Contains Conditional Operator

Windows PowerShell -Contains

When it comes filtering, or finding data we are spoilt for choice with -Match, -Like and -Contains.  While there is overlap, each conditional operator has a distinctive role in PowerShell scripting.

-Contains is best for seeking an exact value.  If I want a command to return either True or False, I start with -Contains, whereas, if I want a list of results then I try -Match or -Like.

Topics for PowerShell's -Contains Conditional Operator


Example 1a: PowerShell -Contains

PowerShell uses singular nouns; thus "contains" is a verb, and not a plural noun.  A feature of -Contains is that usually returns "True" or "False.  If you are looking for a command to return a list of values, then employ -Match or -Like.

# PowerShell -Contains Operator
$ArraySimple =@("House","Flat","Bungalow")
$ArraySimple -Contains "Flat"

# Result PS> True

Example 1b: PowerShell's -Contains is Very Strict

-Contains can be frustrating because it's so picky.  After a while you realize that this just a design feature, if you don't like it, try -Match.

# PowerShell -Contains Operator
$ArraySimple =@("House","Flats","Bungalow")
$ArraySimple -Contains "Flat"

# Result PS> False

Note 1: -Contains interprets "Flats" and "Flat" as different, thus returns False; it does not matter that Flat is a subset of Flats.

Challenge: Substitute -Match for -Contains.

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Example 2: Seeking a Value in a Collection

-Contains would be my choice of conditional operators for situations where I wanted to test for one particular item in a collection, array or a hashtable.

# PowerShell -Contains
$Collection = "Peter Smith", "Paula Harris", "Joan Evans"
$Collection -Contains "Paula"

# Result PS> False

Note 2: If you coded: $Collection -Contains "Paula Harris"
The result would be: True.  You need an exact match of the full item.

Note 3: $Collection -Contains "Paula*" does not help.  Wildcards are next to useless with -Contains.  Better: try -Match Paula, or -Like Paula*

Example 3: PowerShell -Contains SpreadsheetPowerShell -Contains

Let us assume we wish to search in a file called links.csv.  Furthermore, we can use Import-Csv to read the data so that we can test values with -Contains.

My spreadsheet is called links.csv
I stored the file in D:\PowerShell
The column name is "Custom channel"
See screenshot to the right.

# PowerShell -Contains Operator
$File = "D:\Powershell\links.csv"
$Check = (Import-Csv $File)."Custom channel"
$Check -Contains "linktop"

# Result PS> True

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Example 4: PowerShell -CContains

As with PowerShell's other conditional operators, you can force them to be case sensitivity by preceding the command with a 'C'; CContains is not a typo!

# PowerShell -Contains Operator
$File = "D:\Powershell\links.csv"
$Check = (Import-Csv $File)."Custom channel"
$Check -CContains "linktop"

# Result PS> False

Note 4: The point is that in the spreadsheet the value is clearly 'LinkTop', when we force case-sensitivity with CContains, this is not the same as 'linktop', hence a False result.

Example 5: PowerShell -NotContains

The negative -NotContains is not as useful as -NotMatch.  However, from what we have already learned the syntax is predictable.

# PowerShell -Contains Operator
$File = "D:\Powershell\links.csv"
$Check = (Import-Csv $File)."Custom channel"
$Check -NotContains "link"

# Result PS> True

Note 5: Remember that with -Contains, and by extension -NotContains, the match has to be exact.  There is no 'Custom channel' with the name of precisely 'link'.

See more on PowerShell's -Like comparisons ยป

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# For even more information about PowerShell Operators try:

Get-Help about_Operators

Here is the List of the Types of PowerShell's Operators

  • Arithmetic (+ * - /)
  • Assignment (= also -= +=)
  • Comparison ( -Match and -Like; also: -eq -gt)
  • Logical ( -And -Not)
  • Redirectional ( > )
  • Split and Join ( -split)
  • Type (-Is -Isnot)
  • Unary ($i++)

See also PowerShell's -Match »

Summary of PowerShell's -Contains Conditional Operator

When you seek an exact value, then -Contains would be my first choice of conditional operator.  -Match or -Like are better suited to scenarios where you only need a partial match, or you need a list of items.

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See more Windows PowerShell flow control examples

PowerShell Home  • PowerShell If Statement  • PowerShell ElseIf   • Free Permissions Analyzer

Conditional Operators  • PowerShell -Match  • PowerShell -Like  • PowerShell -Contains

PowerShell Comparison Operators  • PowerShell Syntax   • Where Filter  • PowerShell Else

Please email me if you have a better example script. Also please report any factual mistakes, grammatical errors or broken links, I will be happy to correct the fault.



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