Question

I am very new to PowerShell scripting and was experimenting with Function. This is the code I wrote:

Function Add
{
   $sum = 0;
   for($i = 0; $i -le $args.length; ++$i)
   {
     [int] $num = $args[$i]
     $sum += $num
   }
   Write-Output "Sum is $sum"
}

And I tried to call using Add 1,2,3. However, when I execute I get the following error:

Cannot convert the “System.Object[]”
value of type “System.Object[]” to
type “System.Int32”.

Any idea how to fix this?

Answer 1

There’s a bg trap in Powershell: , is the array operator. Try this at the command line:

PS> 1,2,3

You’ll see that it’s an array:

PS> (1,2,3).gettype()
IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     Object[]                                 System.Array

Try to call Add without commas:

PS> Add 1 2 3
Sum is 6

Don’t forget everything is an object in Powershell. You are playing on top of .NET.

So you have two friends:

1. The gettype() method which gives you the type of an object
2. The Get-Member CmdLet which helps you on properties and methods of an object

Get-member has many parameters that can help.