How can I find the index of a String array element using the [Array]::FindIndex method in PowerShell?

Question

another PowerShell noob question.

I have an array of strings that contains the names of businesses and I am writing a script that iterates through the folders of a directory and compares the folder names to the names contained in the array. When I find a match I need to get the array index where the match was found. I've done this successfully for exact matches using the following code:

foreach($file in Get-ChildItem $targetDirectory)
{
    if($businesses -like "$file*")
    {
        $myIndex = [array]::IndexOf($businesses, [string]$file)
    }
}

The reason I use -like "$file*" is because sometimes the name of the business has "LLC" or "INC" or something like that, which occasionally wasn't included when we named the folders(and vice versa). I would like to modify my $myIndex line to find these indexes as well.

I'm trying to use

 $myIndex = [array]::FindIndex($Merchant, {args[0] -like "$file*"})

But I'm getting the error

Cannot find an overload for "FindIndex" and the argument count: "2".

I've tried casting the second argument using [Predicate[string]]{args[0] -like "$file*"} but get the same result. I've read the documentation for the method but one of my basic problems is I don't understand the System.Predicate type. I'm not even sure if I'm writing it properly; I found an example that was similar but used [int] instead. Maybe I'm going about it all wrong but I feel like I'm close and just can't find the missing piece of the puzzle anywhere.

Thanks in advance for any help.

Mathias R. Jessen · Accepted Answer · 2015-08-20 23:09:59Z

5

[Array]::FindIndex($Merchant, [Predicate[string]]{}) only works if $Merchant is of type string[]:

$Merchant is a string array, works:

PS C:\> $Merchant = 1,2,3 -as [string[]]
PS C:\> [array]::FindIndex($Merchant,[Predicate[String]]{param($s)$s -eq "3"})
2

$Merchant is an array of Int32s, doesn't work:

PS C:\> $Merchant = 1,2,3 -as [int[]]
PS C:\> [array]::FindIndex($Merchant,[Predicate[String]]{param($s)$s -eq "3"})
Cannot find an overload for "FindIndex" and the argument count: "2".
At line:1 char:1
+ [array]::FindIndex($Merchant,[Predicate[String]]{param($s)$s -eq "3"})
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodException
    + FullyQualifiedErrorId : MethodCountCouldNotFindBest

Works fine when cast to Predicate[int]:

PS C:\> [array]::FindIndex($Merchant,[Predicate[int]]{param($s)$s -eq 3})
2

answered Aug 20, 2015 at 23:09

Mathias R. Jessen

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1 Comment

jdebr Over a year ago

Okay that's kind of how I thought it would work, thank you for the clarification. However I still get the same error even when I try your examples. Could I be using the wrong version? I'm pretty sure I have version 2.0

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