PowerShell 3.0 -NotIn and -In

New PowerShell 3.0 Comparators -NotIn and -In

PowerShell 1.0 not only has comparison operators such as -Match, -Like and -Contains, but also their negative counterparts such as -NotContains. 

Here in PowerShell 3 we have two new members of the comparsion operators team: -In and -NotIn.

Windows PowerShell -In Topics


Example 1: Testing Numbers in a Range

In this example we are asking PowerShell the question: ‘Is 77 in the range 70 to 80?’

# PowerShell -In
77 -In 70..80

Note 1: The key to using -In (and -NotIn) is mastering the ranging dots .. between the values

Example 2: PowerShell’s -NotIn

Once you have mastered the -In comparator, you’ll have no trouble with its sister command -NotIn, it works in a complimentary manner in according to what logic would predict.

# PowerShell -NotIn
5 -NotIn 70..80

The Secret to Understanding PowerShell 3’s -In and -NotIn

The easiest way to learn which comparator to choose for which script is to compare them!  That is how I appreciated the nuances of -Like and -Match.  In the case of -In, substitute -Contains and observe the similarities and differences.  For me, it all comes down to those two ranging dots, which -In loves, but -Contains seems to ignore.

# Windows PowerShell -Contains
77 -Contains 70..80

Note 2: This makes no sense, thus abandon -Contains and go back to -In.  See Example 2 above

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Comparing Windows PowerShell’s -In with -Match

# PowerShell -Match
‘8080’ -Match ’80’

But ’80’ -Match ‘8080’ would be False

# PowerShell -In
‘8080’ -In ’80’

Also ’80’ -In ‘8080’ would be False

Conclusion:  PowerShell’s -In works best with a range expressed as: 0..8080.  In my opinion -In (or -NotIn) are rarely the best comparison operator for text.

# PowerShell -In
’80’ -In ‘1..8080’

Troubleshooting PowerShell -In and -NotIn

Incorrect version of PowerShell

You must provide a value expression on the right-hand side of the ‘-‘ operator.
At line:2 char:6

Unexpected token ‘in’ in expression or statement.

This is what you get in PowerShell 1.0 or 2.0, -In is new in PowerShell 3.0

You get the ‘wrong’ result, 'False' when all logic tells you it should be true.  Check you have two ranging dots .. and not three … dots. Strange but true!

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Further Research on Conditional Operators

-In and -NotIn are members of PowerShell's conditional operators.  A good way to research these operators is with:

Help about_Comparison_Operators


See more of what’s new in PowerShell v 3.0 »

Summary of PowerShell -In and -NotIn

PowerShell 1.0 uses comparison operators such as, -Match, -Like and -Contains, PowerShell 3.0 brings -In and -NotIn.  The key to understanding these latest operators is to pay close attention to the ranging .. dots.

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See more Microsoft PowerShell v 3.0

PowerShell 3.0  • What’s New in PowerShell 3.0  • PowerShell 3.0 Foreach-Object

PowerShell Show-Command  • Out-GridView -PassThru  • PowerShell Ordered Hash Tables

PowerShell Home  • PowerShell 3.0 Get-ChildItem  • PowerShell 3 -NotIn  • PowerShell 3.0 Where