How to match first characters with a powershell script - regex

Question

I am trying to move files to a certain folder if they start with a letter and delete them if they start with anything other than a letter.
My code:
Function moveOrDelete($source, $dest)
{
$aToZ = '^[a-zA-Z].*'
$notALetter = '^[^a-zA-Z].*'
Get-ChildItem -Path $source\$aToZ -Recurse | Move-Item -Destination $dest
Get-ChildItem -Path $source\$notALetter -Recurse | Remove-Item
}
As I understand it the caret will match on the first character when it's outside of the brackets. In other words, the regex in the $aToZ variable will match anything that begins with a letter. the .* part will allow the rest of the file name to be anything. The caret inside the brackets negates the statement so if the file name begins with anything other than a letter it will match. I can't get it to work and I'm not getting any errors which leads me to believe that my regex is wrong.
I have checked this with online tools including this one: https://regex101.com/ and they check out.
I have also used variations of the regex like ^[a-zA-Z] that don't work. Some patterns like [a-zA-Z]* move the files but it's not the pattern that I want.
Here is how I'm calling the funcion:
moveOrDelete ".\source" ".\dest"
And here are the sample file names I'm using:
a.txt
z.txt
1.txt
.txt

Answer 1

The -Path argument doesn't understand regular expressions, it takes a string and can perform wildcarding but not complex string processing.
So, you need to check the name of each file against the regex with the -match operator. The following should help:
Function moveOrDelete($source, $dest)
{
$aToZ = '^[a-zA-Z].*'
$notALetter = '^[^a-zA-Z].*'
Get-ChildItem -Path $source -Recurse | Where-Object { $_.name -match $aToZ } | Move-Item -Destination $dest
Get-ChildItem -Path $source -Recurse | Where-Object { $_.name -match $notALetter } | Remove-Item
}
Here, you need to filter the file names with the Where-Object cmdlet, then pipe to the move or remove.