Array Types In Powershell - System.Object[] vs. arrays with specific types

Question

Why does caling GetType().Name on an array of strings return Object[] and not String[]? This seems to happen with any element type, for example Import-Csv will give you an Object[] but each element is a PSCustomObject.

Here's an example with an array of String

$x = @('a','b','c')

$x[0].GetType().Name #String
$x.GetType().Name #Object[]

Answer 1

Because you have not specified the data type of the array explicitly.

For instance, assigning an integer to $x[1] would work, because the array's type is Object[].

If you specify a data type while constructing the array, you won't be able to assign values of an incompatible type later:

C:\PS> [int[]] $myArray = 12,64,8,64,12

C:\PS> $myArray.GetType()

IsPublic IsSerial Name                                     BaseType                   
-------- -------- ----                                     --------                   
True     True     Int32[]                                  System.Array               



C:\PS> $myArray[0] = "asd"
Cannot convert value "asd" to type "System.Int32". Error: "Input string was not in a c
orrect format."
At line:1 char:1
+ $myArray[0] = "asd"
+ ~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvalidCastFromStringToInteger