Can strings be null in Powershell?

Question

Why, in this powershell code, does the last statement resolve to true?

PS C:\> $s = [System.String]$null
PS C:\> $s.GetType()
IsPublic IsSerial Name                                     BaseType                                                                  
-------- -------- ----                                     --------                                                                  
True     True     String                                   System.Object 
PS C:\> $s -eq ""
True

Yes, or even `[System.String]$s=[System.String][NullString]::Value`. The meaning of the [variable `$null`](https://technet.microsoft.com/en-us/library/hh847768.aspx) is NULL ___or___ an empty value. Somewhat related to [Possible to pass null from Powershell to a .Net API that expects a string?](http://stackoverflow.com/questions/2002570/) — Jeppe Stig Nielsen, Oct 17 '16 at 12:58

score 1 · Answer 1 · edited May 23 '17 at 10:32

1

PowerShell always converts null strings to empty string Check accepted answer here for details : Passing null to a mandatory parameter to a function

edited May 23 '17 at 10:32

Community

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answered Apr 07 '16 at 00:33

smichaud

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Sure, but the details there don't go into the question of why. It would be nice to understand the motivation here. – Paul Raff Apr 07 '16 at 01:06

score 1 · Answer 2 · answered Apr 07 '16 at 22:33

1

Basically so you never have to write string.IsNullOrEmpty() or get a null reference on a string in PowerShell. See Tony Hoare "Null References: The Billion Dollar Mistake".

answered Apr 07 '16 at 22:33

Bruce Payette

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Can strings be null in Powershell?

2 Answers2