Passing integer array as command line argument to powershell script

Question

I have the following powershell script:

param (
  [Parameter(Mandatory=$true)][int[]]$Ports
)

Write-Host $Ports.count

foreach($port in $Ports) {
 Write-Host `n$port
}

When I run the script with $ powershell -File ./test1.ps1 -Ports 1,2,3,4 it works (but not as expected):

1

1234

When I try to use larger numbers, $ powershell -File .\\test.ps1 -Ports 1,2,3,4,5,6,10,11,12 , the script breaks entirely:

test.ps1 : Cannot process argument transformation on parameter 'Ports'. Cannot convert value "1,2,3,4,5,6,10,11,12" to type "System.Int32[]". Error: "Cannot convert value "1,2,3,4,5,6,10,11,12" to type "System.Int32". Error: "Input
string was not in a correct format.""
    + CategoryInfo          : InvalidData: (:) [test.ps1], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : ParameterArgumentTransformationError,test.ps1

It seems like powershell is trying to process any numbers passed via the Ports param as a single number, though I'm not sure why this is happening, or how to get past it.

Answer 1

The issue is that a parameter passed through powershell.exe -File is a [string] .

So for your first example,

powershell -File ./test1.ps1 -Ports 1,2,3,4

$Ports is passed as [string]'1,2,3,4' which then attempts to get cast to [int[]] . You can see what happens with:

[int[]]'1,2,3,4'
1234

Knowing that it will be an just a regular [int32] with the comma's removed means that casting 1,2,3,4,5,6,10,11,12 will be too large for [int32] which causes your error.

[int[]]'123456101112'

Cannot convert value "123456101112" to type "System.Int32[]". Error: "Cannot convert value "123456101112" to type "System.Int32". Error: "Value was either too large or too small for an Int32.""

---

To continue using -file you could parse the string yourself by splitting on commas.

param (
    [Parameter(Mandatory=$true)]
    $Ports
)

$PortIntArray = [int[]]($Ports -split ',')

$PortIntArray.count    

foreach ($port in $PortIntArray ) {
    Write-Host `n$port
}

But luckily that is unnecessary because there is also powershell.exe -command . You can call the script and use the PowerShell engine to parse the arguments. This would correctly see the Port parameter as an array.

powershell -Command "& .\test.ps1 -Ports 1,2,3,4,5,6,10,11,12"