Powershell - LIKE against an array

Question

For every file being processed, its name is being checked to satisfy the condition. For example, given the following list of filters:

$excludeFiles = @"
aaa.bbb
ccccc.*
ddddd???.exe
"@ | SplitAndTrim;

It should exclude a file from processing if it matches any of the lines. Trying to avoid match/regex, because this script needs to be modifiable by someone who does not know it, and there are several places where it needs to implemented.

$excludedFiles and similar are defined as a here-string on purpose. It allows the end user/operator to paste a bunch of file names right from the CMD/Powershell window.

It appears that Powershell does not accept -like against an array, so I cannot write like this:

"ddddd000.exe" -like @("aaa.bbb", "ccccc.*", "ddddd???.exe")

Did I miss an option? If it's not natively supported by Powershell, what's the easiest way to implement it?

See answer from Josh Einstein: stackoverflow.com/questions/848859/… — dugas
– dugas, Commented Oct 22, 2012 at 22:35
Thanks, @dugas, but I don't see why those complications - compare to the two lines below - see my accepted answer. — Victor Zakharov
– Victor Zakharov, Commented Oct 23, 2012 at 1:18
It converts the right side to a string, "aaa.bbb ccccc.* ddddd???.exe". Btw you don't need @( ) — js2010
– js2010, Commented Nov 17 at 13:26
Regex is the obvious answer -match "aaa.bbb|ccccc.|ddddd....exe" — js2010
– js2010, Commented Nov 18 at 14:51

davidhigh · Accepted Answer · 2016-08-12 12:07:22Z

16

Here is a short version of the pattern in the accepted answer:

($your_array | %{"your_string" -like $_}) -contains $true

Applied to the case in the OP one obtains

PS C:\> ("aaa.bbb", "ccccc.*", "ddddd???.exe" | %{"ddddd000.exe" -like $_}) -contains $true
True

edited Aug 12, 2016 at 12:07

answered Aug 12, 2016 at 10:59

davidhigh

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6 Comments

Thomas Nov 13 at 6:29

This is worse than the accepted answer in performance; the accept answer make use of break to skip evaluation of items after finding a match, while this answer maps every single string to a boolean.

davidhigh Nov 16 at 17:45

Performance often doesn't matter for this kind of tasks, and if it does, I would go with neither this or the accepted answer. Conciseness, on the other hand, is usually a good thing to have. So, as always, feel free to use what you prefer.

Thomas Nov 16 at 18:25

I'm made the comment because in your answer you said "Here is a short version of the pattern in the accepted answer", which isn't technically true. But yeah I see your point

davidhigh Nov 16 at 20:56

Ok, I see your's as well, not true indeed :-)

Thomas Nov 17 at 4:52

I'm curious as to what solution you would use for performance as well? I thought powershell's foreach function in the accepted answer is pretty good already 🤔

Thomas Nov 17 at 4:53

If you have time to spare could you please look at my answer as well

Victor Zakharov · Accepted Answer · 2012-10-23 01:27:44Z

11

You can perform a pattern match against a collection of names, but not against a list of patterns. Try this:

foreach($pattern in $excludeFiles)
{
    if($fileName -like $pattern) {break}
}

Here is how it can be wrapped into a function:

function like($str,$patterns){
    foreach($pattern in $patterns) { if($str -like $pattern) { return $true; } }
    return $false;
}

edited Oct 23, 2012 at 1:27

Victor Zakharov

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answered Oct 22, 2012 at 20:56

Shay Levy

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3 Comments

Victor Zakharov Over a year ago

That's what I thought at first... just don't like the idea of having to implement this loop every time I need this functionality. I will accept this answer, if nobody else provides an alternative.

Shay Levy Over a year ago

Wrap it in a function and reuse it :)

Victor Zakharov Over a year ago

That's exactly what I did - I also updated your answer to include my solution.

Victor Zakharov · Accepted Answer · 2012-10-23 01:29:35Z

4

I suppose you could use the Get-ChildItem -Exclude parameter:

Get-ChildItem $theFileToCheck -exclude $excludeFiles

If you have an array of files to check, Get-ChildItem accepts an array of paths:

Get-ChildItem $filesToCheck -exclude $excludeFiles

edited Oct 23, 2012 at 1:29

Victor Zakharov

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answered Oct 22, 2012 at 22:38

zdan

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2 Comments

Victor Zakharov Over a year ago

Thanks - I can confirm that Get-ChildItem or simply dir (I am more used to Windows terminology) correctly excludes by the same pattern as LIKE, and it works for an array of strings, which can be very convenient for many uses. Unfortunately, it does not work for my needs, because in some cases I need to work with strings directly, not file objects. Still, your answer deserves a +1.

mems Jan 27 at 15:18

It doesn't work is the wildcard in the pattern is not at the beginning

Jesse Motes · Accepted Answer · 2019-10-04 18:23:43Z

2

$excludeFiles.Where{$stringToTest -like $_}

Powershell array has a Where method that can take an expression input, hence the {} instead of (). Feed in a string to test and it will iterate over the array using the standard pipe so $_ represents the element of the array.

Outputs a list of matching elements.

PS H:\> $excludeFiles = @("aaa.bbb", "ccccc.*", "ddddd???.exe")
PS H:\> $stringToTest = "ddddd000.exe"
PS H:\> $excludeFiles.Where{$stringToTest -like $_}
ddddd???.exe

answered Oct 4, 2019 at 18:23

Jesse Motes

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Comments

Thomas · Accepted Answer · 2025-11-17 05:03:14Z

To deal with your problem and all similar existential quantification related problems, we might want a generic solution that allows us to do something like:

PS> "aaa.bbb", "ccccc.*", "ddddd???.exe"| any { "ddddd000.exe" -like $_ }
True


PS> "aaa.bbb", "ccccc.*", "ddddd???.exe"| any { "ddd000.exe" -like $_ }
False

Solution: Utility function `Test-Any`

Simply put this function in your (profile) scripts:

function Test-Any {
    <#
        .SYNOPSIS
            Check if any element satisfies a predicate, returns a boolean.
        .PARAMETER InputObject
            Prefer using pipeline over parameter.
            Scalar argument provided through parameter will be wrapped into an array.
        .PARAMETER Predicate
            ScriptBlock function: ([Object]$Element) -> [Boolean]$Result
        .EXAMPLE
            Test-Any -InputObject 1,2,3,4 {$_ % 2}
            True
        .EXAMPLE
            1,(2,3),4 | Test-Any {$_.Count -eq 3}
            False
    #>
    [CmdletBinding()]
    param(
        [Parameter(Mandatory, ValueFromPipeline)][AllowNull()]
        [Object]$InputObject,
        [Parameter(Mandatory, Position = 0)][ArgumentCompletions('{}')]
        [ScriptBlock]$Predicate
    )
    # Replace `$InputObject` with pipeline value, if value is provided from pipeline.
    if ($MyInvocation.ExpectingInput) { $InputObject = $input }
    else { $InputObject = @($InputObject) }

    foreach ($o in $InputObject) {
        if ($Predicate.InvokeWithContext($null, [PSVariable]::new('_', $o))) {
            return $true
        }
    }
    return $false
}

I would also recommend adding the alias any for ease of use:

New-Alias -Name any -Value Test-Any

Bonus: Utility function `Test-All`

Might as well have a function for universal quantification too!

function Test-All {
    <#
        .SYNOPSIS
            Check if all elements satisfy a predicate, returns a boolean.
        .PARAMETER InputObject
            Prefer using pipeline over parameter.
            Scalar argument provided through parameter will be wrapped into an array.
        .PARAMETER Predicate
            ScriptBlock function: ([Object]$Element) -> [Boolean]$Result
        .EXAMPLE
            1,2,3,4 | Test-All {$_ % 2}
            False
        .EXAMPLE
            1,3,5 | Test-All {$_ % 2}
            True
    #>
    [CmdletBinding()]
    param(
        [Parameter(Mandatory, ValueFromPipeline)][AllowNull()]
        [Object]$InputObject,
        [Parameter(Mandatory, Position = 0)][ArgumentCompletions('{}')]
        [ScriptBlock]$Predicate
    )

    # Replace `$InputObject` with pipeline value, if value is provided from pipeline.
    if ($MyInvocation.ExpectingInput) { $InputObject = $input }
    else { $InputObject = @($InputObject) }

    foreach ($o in $InputObject) {
        if (!$Predicate.InvokeWithContext($null, [PSVariable]::new('_', $o))) {
            return $false
        }
    }
    return $true
}

(These functions and their naming are inspired by the ones in Kotlin standard library, any and all).

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