Construct a string parameter to function - powershell

Question

Im wondering how you can construct a string on the fly as a parameter to a function? Example say I have a function like

function MyFunc
{
    Param
         (
              [Parameter(mandatory=$true)] [string] $myString,
              [Parameter(mandatory=$true)] [int] $myInt
         )

    Write-Host ("Param 1 is {0}" -f $myString)
    Write-Host ("Param 2 is {0}" -f $myInt)


}

How can I call it whilst constructing the first string param on the fly e.g.

$myName = "Casper"
$myInt=7

MyFunc "Name is " + $myName $myInt

Ive tried putting {} around the first "bit" like

MyFunc {Name is " + $myName} $myInt

This then incorrectly prints out

Param 1 is "Name is "+$myName
Param 2 is 7

what I want it to print is

Param 1 is "Name is Casper"
Param 2 is 7

I know a better way of doing this would just be to set up the string first,

$pm1 = "Name is " + $myName

and call function MyFunc $pm1 $myInt

but I am just interested to know how it can be done on the fly as it were. How can I construc the string and pass as first parameter on the function call? Hope thats clear.

Thanks

Mathias R. Jessen · Accepted Answer · 2022-04-20 10:55:47Z

2

As a general rule of thumb, you can always nest any complex expression in a separate pipeline using the subexpression operator $(...) or grouping operator (...):

MyCommand $("complex",(Get-Something),"argument","expression" -join '-')

But in your particular case we don't need that - you just need to place the variable expression $myName inside the string literal and PowerShell will automatically evaluate and expand its value:

MyFunc "Name is $myName" $myInt

If the variable expression is to be followed by some characters that would otherwise make up a valid part of the variable path, use curly brackets {} as qualifiers:

MyFunc "Name is ${myName}" $myInt

answered Apr 20, 2022 at 10:55

Mathias R. Jessen

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1 Comment

Keith Over a year ago

Thats perfect thanks. The $() bit is what I needed to know.

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