How do I filter a string array (or list) in PowerShell using the 'Match' cmdlet?

Question

I am trying to filter CSV files. But the following script is giving an error. How do I specify that I want to run match on each String object?

I tried various combinations, but without result.

$FileNames = [System.IO.Directory]::GetFiles("C:\Users\anagre\Desktop")

$FileNames = $FileNames | Where { -match "*.csv"}

Answer 1

Try this:

$FileNames = Get-ChildItem -Path "C:\Users\anagre\Desktop" -Filter *.csv

In your above code you didn't use the $PSItem ($_) in your where clause, and if you want to use a wildchar you have got to use the -like operator:

$FileNames|where{$_ -like "*.csv"}

or

$FileNames|where{$_ -match ".csv"}

Answer 2

The -match operator is both a comparison operator and an array operator, depending on its input object.

If it's a scalar, it returns a boolean. If it's an array, it returns all the elements of the array that match the pattern

@($Filenames) -match '*.csv'

Use the array syntax to ensure that you still get an array if there's only one filename returned by Get-ChildItem. Otherwise, you'll get back $True instead of the filename if it matches.

Answer 3

The simplest (and tidiest) way I found to do this was as follows:

$filename.where{$_ -match '.csv'}

or to only search within a given column of a hashtable

$filename.where{$_.location -match '.csv'}

Then get just the bits you need

$filename.where{$_.location -match '.csv'} | select User,Filename,Filetype

etc