Create new System.Collections.Generic.Dictionary object fails in PowerShell - powershell

Question

PowerShell version: 5.x, 6
I'm trying to create a new object of System.Collections.Generic.Dictionary, but it fails.
I tried the following "versions":
> $dictionary = new-object System.Collections.Generic.Dictionary[[string],[int]]
New-Object : Cannot convert 'System.Object[]' to the type 'System.String' required by parameter 'ComObject'. Specified method is not supported.
At line:1 char:25
+ ... ry = new-object System.Collections.Generic.Dictionary[[string],[int]]
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidArgument: (:) [New-Object], ParameterBindingException
+ FullyQualifiedErrorId : CannotConvertArgument,Microsoft.PowerShell.Commands.NewObjectCommand
> $dictionary = new-object System.Collections.Generic.Dictionary[string,int]
New-Object : Cannot convert 'System.Object[]' to the type 'System.String' required by parameter 'ComObject'. Specified method is not supported.
At line:1 char:25
+ ... ionary = new-object System.Collections.Generic.Dictionary[string,int]
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidArgument: (:) [New-Object], ParameterBindingException
+ FullyQualifiedErrorId : CannotConvertArgument,Microsoft.PowerShell.Commands.NewObjectCommand
I know that I can use a hashtable under PowerShell, but I want to know how to create a dictionary via the above declaration.
What am I missing?
Thx

Answer 1

Used type name System.Collections.Generic.Dictionary[[string],[int]] contains a comma. By Creating and initializing an array:
To create and initialize an array, assign multiple values to a
variable. The values stored in the array are delimited with a
comma…
Hence, you need to escape the comma (read the about_Escape_Characters and about_Quoting_Rules help topics). There are more options:
In Windows PowerShell, the escape character is the backtick (`),
also called the grave accent (ASCII 96).
$dictionary = new-object System.Collections.Generic.Dictionary[[string]`,[int]]
Quotation marks are used to specify a literal string. You can enclose
a string in single quotation marks (') or double quotation marks
(").
$dictionary = new-object "System.Collections.Generic.Dictionary[[string],[int]]"
or
$dictionary = new-object 'System.Collections.Generic.Dictionary[[string],[int]]'

Answer 2

The problem is how powershell is interpreting your argument.
When you include a comma in your string, it's now trying to bind
'System.Collections.Generic.Dictionary[[string]', '[int]]'
to the -TypeName parameter which is of type <string[]> or in the error message, <System.Object[]>. This can be solved by properly quoting your argument so it matches the expected parameter binding of <string>:
New-Object -TypeName 'System.Collections.Generic.Dictionary[[string], [int]]'

Answer 3

As well as the accepted answer, a dictionary can also be initialised using the syntax in the code block below, which:
removes the need to escape any characters
is much cleaner (in my opinion)
gives you intellisense (tested in PowerShell & PowerShell ISE)
$dictionary = [System.Collections.Generic.Dictionary[string,int]]::new()
... where string and int are .NET types.