Why does a new parameter change the behavior of my powershell function?

Question

As the title already says I'm very confused about my simple PowerShell script

function create_dir([array]$folders)
{
    $dir = "D:\test\New Folders"
    

    foreach ($folder in $folders)
    {
        Write-Host $folder
        New-Item -Path $dir -Name $folder -ItemType "directory" -Force
    }
}


$test_path = "D:\test\New Folders"
$my_folders = @("txt","png","jpg", "c")

create_dir($folders)

When I run this everything works fine and as intended (the folders get created).

Mode LastWriteTime Length Name

d----- 20.04.2022 11:11 txt
png d----- 20.04.2022 11:11 png
jpg d----- 20.04.2022 11:11 jpg
c d----- 20.04.2022 11:11 c

But when I now add a string to the parameterlist like this:

function create_dir([string]$test, [array]$folders)
{
    $dir = "D:\test\New Folders"
    

    foreach ($folder in $folders)
    {
        Write-Host $folder
        New-Item -Path $test -Name $folder -ItemType "directory" -Force
    }
}


$test_path = "D:\test\New Folders"
$my_folders = @("txt","png","jpg", "c")

create_dir($test_path, $my_folders)

It stops working but I dont get any errors. As my Array would suddently be empty or soemthing...

$test_path = "D:\test\New Folders" $my_folders = @("txt","png","jpg", "c")

create_dir($test_path, $my_folders)

Can you guys please help me?

In `create_dir($test_path, $my_folders)` you are actually constructing an array of `$test_path` and `$my_folders` and pass that as a _single_ argument to the function. Proof: `function fun($a,$b){ "a: $a"; "b: $b" }; fun(1,2)`. PowerShell functions have to be called without parentheses, like shell commands: `create_dir $test_path $my_folders`. — zett42, Apr 20 '22 at 11:33
Does this answer your question? [PowerShell's parsing modes: argument (command) mode vs. expression mode](https://stackoverflow.com/questions/48776180/powershells-parsing-modes-argument-command-mode-vs-expression-mode) — zett42, Apr 20 '22 at 11:34

score 0 · Accepted Answer · edited Apr 20 '22 at 10:53

0

I'm not sure how your first script worked since the parameter you sent "$folders" wasn't defined anywhere.

But to answer your question just pass the parameters/call your function without the parenthesis and comma.

Ex. create_dir $test_path $my_folders

edited Apr 20 '22 at 10:53

Theo

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answered Apr 20 '22 at 10:10

Rass Rigor

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Why does a new parameter change the behavior of my powershell function?

1 Answers1