About Using



Allows to indicate which namespaces are used in the session.


The using statement allows to indicate which namespaces are used in the session. Making easier to mention classes and members, as it requires less typing to mention them; also, classes from modules can be referenced too.

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

Syntax #1, to reference .Net Framework namespaces:

using namespace <.Net-framework-namespace>

Syntax #2, to reference PowerShell modules:

using module <module-name>

Note The using statetement, for modules, is intended to surface the classes in the module. If the module isn't loaded, the using fails.

Example 1

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, to [Stream] and to [MemoryStream] in System.IO.

    using namespace System.Text
    using namespace System.IO

    [string]$string = "Hello World"
    [string]$algorithm = "SHA256" ## Valid values are "SHA1", "SHA256", "SHA384", "SHA512", "MACTripleDES", "MD5", "RIPEMD160"

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

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

Example 2

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)