Powershell Convert String[] to List

Question

I have this code: ``` $csvUserInfo = @([IO.File]::ReadAllLines($script:EmailListCsvFile)) $x = $csvUserInfo.ToList() ``` When it runs, I get this error: ``` Method invocation failed because [System.String] does not contain a method named 'ToList'. ``` Why is $csvUserInfo of type String? Doesn't [IO.File]::ReadAllLines return a string[] ? I've tried with/without the @ as well, it makes no difference.

Accepted Answer

No, you are right. As shown here, `[IO.File]::ReadAllLines` does return a `String[]` object. The confusing error that you are seeing is explained in @mjolinor's answer (I won't repeat it here).

Instead, I will tell you how to fix the problem. To convert a `String[]` object into a `List<String>` object in PowerShell, you need to explicitly cast it to such:

```
PS > [string[]]$array = "A","B","C"
PS > $array.Gettype()

IsPublic IsSerial Name                                     BaseType                                      
-------- -------- ----                                     --------                                      
True     True     String[]                                 System.Array

PS > 
PS > [Collections.Generic.List[String]]$lst = $array
PS > $lst.GetType()

IsPublic IsSerial Name                                     BaseType                                      
-------- -------- ----                                     --------                                      
True     True     List`1                                   System.Object

PS >
```

In your specific case, the code would be:

```
$csvUserInfo = [IO.File]::ReadAllLines($script:EmailListCsvFile)
[Collections.Generic.List[String]]$x = $csvUserInfo
```

Powershell Convert String[] to List<String>

Solution

Problem