Convert Arraylist to string in powershell

Question

I am trying to grep some data from a variable:

 Select-String -inputObject $patternstring  -Pattern $regex -AllMatches
 | % { $_.Matches } | % { $_.Value } -OutVariable outputValue
 Write-Host $outputValue

To the same outvariable, I am trying to do string manipulation

$outputValue.Substring(1,$outputValue.Length-2);

this fails stating that outputValue is an ArrayList.

How can I convert an Arraylist to String?

Solution 1

As mentioned in sean_m's comment, the easiest thing to do is to simply first convert the System.Collections.ArrayList of strings to a single string by using the -join operator:

$outputValue = $($outputValue -join [Environment]::NewLine)

Once you have done this you can perform any regular string operations on $outputValue, such as the Substring() method.

Above I separate each string in the ArrayList with a new line, as that's typically the string that the -OutVariable splits the string on when converting it to an ArrayList, but you can use a different separator character/string if you want.

Solution 2

Try like this:

$outputvalue = Select-String -inputObject $patternstring  -Pattern $regex -AllMatches | 
               % { $_.Matches } | % { $_.Value }
$outputValue | % { $_.Substring(1 ,$_.Length - 2)}

The parameter -outvariable in the ForEach-Object doesn't seem to capture the output of the sciptblock processed ( This in Powershell V2; thank to @ShayLevi for testing it works in V3).

Solution 3

If the output is a collection of values then no matter what the type of the result is , substring should fail. Try to pipe to Foreach-Object and then use substring.

UPDATE:

The OutputVariable works only in v3, see @Christian solution for v2.

Select-String -InputObject $patternstring  -Pattern $regex -AllMatches  | % { $_.Matches } | % { $_.Value } -OutVariable outputValue
$outputValue | Foreach-Object { $_.Substring(1,$_.Length-2) }

Comments

[CB.]

I tested this way but seem that in this foreach the -outvariable isn't populate. Can you confirm this issue? thanks

[Shay Levy]

You're right, I was testing on v3 and it worked. It failed in v2. In any case, the result is System.String, not ArrayList.

[Shay Levy]

+1, anyway, I think you need to pipe the result to foreach in case the result is a collection, otherwise substring will fail.

[CB.]

@shayLevy Sure! Have forgot to paste the rigth command. Edited my answer.. again :)

[CB.]

+1 But isn't it Foreach-Object { $_.Substring(1,$_.Length-2) } ?

[Shay Levy]

Correct again, it is fixed now :)