How to retain trailing zeros in string array parameter without using quotes

Question

PowerShell drops the trailing zero of an array element's value when that value contains a dot. Unless I wrap the value in quotes. Unfortunately I need to retain the trailing zero and the script users fail to use quotes reliably.

How can I coerce PowerShell to preserve the trailing zero?

• The array element format is Number.Number
• The array element may have 1 to n trailing zeros
• Single element arrays retain trailing zeros
• Multi element arrays drop trailing zeros

Strongly typing the parameter as [string[]] does not resolve the issue.

Example:

function Get-Customer {
    Param 
    ( 
        [string[]]$CustomerId
    )
    $CustomerId
}

> Get-Customer -CustomerId 654.1,654.10,654.1721,654.1720
654.1    #CORRECT
654.1    #INVALID
654.1721 #CORRECT
654.172  #INVALID

Answer 1

You cannot preserve that 0 if the caller does not put it in quotes. The fact is that those values will be interpreted as numbers because they fit the pattern of number literals.

So if you can't change your caller's behavior then they will be numbers before they ever enter your function. Your [string[]] cast will convert the number to a string, but it's already a number at that point and will follow number -> string rules.

PowerShell is very lenient when it comes to type conversion, or rather, it tries hard to successfully convert types when there is a mismatch, so it will be difficult to throw an error in this case too (you have no access to the original values to know anything is wrong as this happens during parameter binding).

You could do this:

function Get-Customer {
    Param 
    ( 
        [ValidateScript({
            $_ -is [string]
        })]
        [object[]]$CustomerId
    )
    $CustomerId
}

It would force the values passed in to already be a [string], which kind of sucks for all the other cases where string conversion would have been useful though.

Answer 2

I'm with briantist, to reduce quoting, you could split one string:

function Get-Customer {
    Param 
    ( 
        [ValidateScript({
            $_ -is [string]
        })]
        [object[]]$CustomerId
    )
    $CustomerId -split ','
}

---

> Get-Customer -CustomerId '654.1,654.10,654.1721,654.1720',"1.000,2.00"
654.1
654.10
654.1721
654.1720
1.000
2.00

Answer 3

How about this trick. No commas, no quotes, still getting an array and maintaining all your items as is, like this...

function Get-CustomerId 
{ $args }
New-Alias -Name cid -Value Get-CustomerId 
cid 654.1 654.10 654.1721 654.1720

# Results

654.1
654.10
654.1721
654.1720