Question

Can someone explain why this script throws an exception?

$byteArray = @(1,2,3)
write-Output ( "{0:X}{1:X}{2:X}" -f $byteArray )
write-Output ( $byteArray.Length -ge 3 )
write-Output ( "{0:X}{1:X}{2:X}" -f $byteArray )

Basically, I am creating an array of numbers, formatting the array and then checking its length and formatting it again.

The first format succeeds, but the second format throws an exception.

123
True
--------------------------------------------------------------------------------
POWERSHELL EXCEPTION 
EXCEPTION TYPE:System.Management.Automation.RuntimeException
MESSAGE:Error formatting a string: Index (zero based) must be greater than or equal to zero and less than the size of the argument list..
POSITION:
At line:4 char:36
+ write-Output ( "{0:X}{1:X}{2:X}" -f  <<<< $byteArray )
--------------------------------------------------------------------------------

Answer 1

That’s definitely weird. As a workaround you can use

"{0:X}{1:X}{2:X}" -f @($byteArray)

which seems to work even after accessing members of $byteArray.

Another possible workaround might be to save the formatted string to a variable and re-use it.

As for why it doesn’t work after accessing the Length property I have no idea.