Concatenate two strings to form an existing variable

Question

I have a folder with multiple PDFs I need to print to different printers. I've created variables for each shared printer and depending on the first 2 letters of the PDF the printing will go to the matching printer.

I'm having trouble concatenating 2 strings to form an existing variable to use it later in the printing call.

This is what I have now (all PDFs in the dir starts with 01 for now):

# SumatraPDF path
$SumatraExe = "C:\Users\Administrador.WIN-FPFTEJASDVR\AppData\Local\SumatraPDF\SumatraPDF.exe"
# PDFs to print path
$PDF = "C:\Program Files (x86)\CarrascocreditosPrueba2\CarrascocreditosPrueba2\DTE\BOL"

# Shared printers list
$01 = '\\192.168.1.70\epson'
$02 = '\\192.168.1.113\EPSON1050'

cd $PDF

While ($true) {
    Get-ChildItem | Where {!$_.PsIsContainer} | Select-Object Name | %{
    $Boleta = $_.Name
    $CodSucursal = $Boleta.Substring(0,2)
    $CodImpresora = '$' + $CodSucursal
    Write-Host $CodImpresora -> This shows literal $01 on PS ISE
    Write-Host $01 -> This show the shared printer path
    }
    Start-Sleep -Seconds 5
}

# Actual PDF printing...
#& $SumatraExe -print-to $CodImpresora $PDF

So basically I need to call an existing variable based on 2 strings. Probably this could be achieved with a Switch but that will be too extensive.

Mathias R. Jessen · Accepted Answer · 2020-08-20 18:22:45Z

concatenating 2 strings to form an existing variable

That won't work in PowerShell, variable tokens are always treated literally.

I'd suggest you use a hashtable instead:

# Shared printers table
$Impresoras = @{
  '01' = '\\192.168.1.70\epson'
  '02' = '\\192.168.1.113\EPSON1050'
}

Then inside the loop:

$Boleta = $_.Name
$CodSucursal = $Boleta.Substring(0,2)
$Impresora = $Impresoras[$CodSucursal]

Although the language syntax don't support variable variable names, you can resolve variables by name using either the Get-Variable cmdlet:

# Returns a PSVariable object describing the variable $01
Get-Variable '01' 

# Returns the raw value currently assigned to $01
Get-Variable '01' -ValueOnly

... or by querying the Variable: PSDrive:

# Same effect as `Get-Variable 01`
Get-Item Variable:\01

While these alternatives exist, I'd strongly suggest staying clear of using them in scripts - they're slow, makes the code more complicated to read, and I don't think I've ever encountered a situation in which using a hashtable or an array wasn't ultimately easier :)

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