About Using


Allows to indicate which namespaces are used in the session.


The using statement allows you to specify which namespaces are used in the session. Adding namespaces simplifies usage of .NET classes and member and allows you to import classes from modules.

The using statement needs to be the first statement in the script.


To reference .NET Framework namespaces:

using namespace <.NET-framework-namespace>

To reference PowerShell modules:

using module <module-name>


Import-Module and the #requires statement only import the module functions, aliases, and variables, as defined by the module. Classes are not imported. The using module statement imports the classes defined in the module. If the module isn't loaded in the current session, the using statement fails.


The following script gets the cryptographic hash for the "Hello World" string.

Note how the using namespace System.Text and using namespace System.IO simplify the references to [UnicodeEncoding] in System.Text and [Stream] and to [MemoryStream] in System.IO.

using namespace System.Text
using namespace System.IO

[string]$string = "Hello World"
## Valid values are "SHA1", "SHA256", "SHA384", "SHA512", "MD5"
[string]$algorithm = "SHA256"

[byte[]]$stringbytes = [UnicodeEncoding]::Unicode.GetBytes($string)

[Stream]$memorystream = [MemoryStream]::new($stringbytes)
$hashfromstream = Get-FileHash -InputStream $memorystream `
  -Algorithm $algorithm

The following script assumes a module named 'CardGames' was loaded automatically.

The following classes are defined in the module:

  • Deck
  • Card
using module CardGames

[Deck]$deck = [Deck]::new()
[Card[]]$hand1 = $deck.Deal(5)
[Card[]]$hand2 = $deck.Deal(5)
[Card[]]$hand3 = $deck.Deal(5)