I have a string where the last char is an index value that I need to perform some math with. As an example the string would be: $temp = c:\temp\junk0
To get the last char I do something like:
$index = $temp[$temp.length-1]
This returns 0 but when I use it with power shell says its a char. So I tried doing:
[int]$index = $temp....
But this returns 48 (I think thats ascii for 0). How can I get this back as a '0'

Thanks

It can only be a single number?

Try it this way instead:
PS>[int]$temp.substring($temp.length-1)

[int][string]"This is a test0"[-1] works fine. ;)
[-1] returns last element in array (string is char array)
[string] will make single-char string
[int] will return string int value

A more complicated, but generic way would be to use a regular expression which extracts the trailing number of the path you are processing:

$folders = @("C:\temp\test1", "C:\temp\test12", "C:\temp\test123", "C:\temp\t35t1234")

$regex = [Regex]'(?< Name >.*\w[^0-9]+?)(?< Index >\d+)$' # Remove the spaces in the angle brackets

foreach ($folder in $folders)
{
    if ($folder -match $regex)
    {
        $Matches["Name"]
        [Int32]$Matches["Index"]
    }
}

[int]"$($temp[-1])"

This is odd, I tried the 1st two responses when I put them inside a script I get some strange object returned that looks like a square. If I try these from the powershell command prompt I get 0 (zero) back.

This is what I get when I run your examples with my solution:

PS H:\RFGExchmig> $temp = 'c:\temp\junk8'

___________________________________________________________________________________________
PS H:\RFGExchmig> $index = [int]"$($temp[-1])"

___________________________________________________________________________________________
PS H:\RFGExchmig> $index.gettype()

IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Int32 System.ValueType



___________________________________________________________________________________________
PS H:\RFGExchmig> $index
8