Get-Date cmdlet outputs wrong year from "FileTime" value.

Steps to reproduce

    $filetime = (Get-Date).ToFileTime()
    'Get-Date: {0:dd.MM.yyyy}' -f (Get-Date $filetime)
    'DateTime: {0:dd.MM.yyyy}' -f [datetime]::FromFileTime($fileTime)

Output:

Get-Date: 18.03.0421
DateTime: 18.03.2021

Expected behavior

Outputting the correct date

Actual behavior

Incorrect year value

Environment data

$PSVersionTable                                         
                                                           
Name                           Value                       
----                           -----                       
PSVersion                      7.1.3                       
PSEdition                      Core                        
GitCommitId                    7.1.3                       
OS                             Microsoft Windows 10.0.19042
Platform                       Win32NT                     
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}       
PSRemotingProtocolVersion      2.3                         
SerializationVersion           1.1.0.1                     
WSManStackVersion              3.0                         

[mklement0]

why Get-Date trying interpret these values is not.

It is clear, as explained - and without an explicit (hypothetical) parameter such as -FromFileTime, what you’re asking for cannot be implemented (see below).

why not give it the same capability as System.Datetime class?

Generally speaking, it is not - and should not - be PowerShell’s goal to replicate all .NET APIs. Instead, PowerShell’s focus is on what matters from a perspective of a shell and automation - though there is substantial overlap, which is what makes PowerShell unique among shells.

Using .NET APIs, the solution is:

[datetime]::FromFileTime($filetime)

This complements your use of a .NET API to obtain the $filetime value to begin with - the .ToFileTime() method.

---

If you feel strongly enough that this functionality should be surfaced via the Get-Date cmdlet as well, I suggest you create a new issue of type “Feature Request/Idea” and ask for:

• -AsFileTime to convert (from [datetime]) TO a FILETIME value
• -FromFileTime to convert FROM a FILETIME value (to a [datetime] instance)

Note: no need for _UTC, as FILETIME values are by definition UTC timestamps.

[237dmitry]

All is clear but why Get-Date trying interpret these values is not. New-Timespan or (Get-Date) - (Get-Date) returns a more obvious result. If Get-Date returns a datetime object, then why not give it the same capability as System.Datetime class? For example:

Get-Date -FromFiletime_Uts_ $filetime

This would be logical to get the FileTime value and return the DateTime object from a single cmdlet. Without resorting to .net methods explicitly. It’s more a matter of style, not convenience. These are small things, but every little thing is important. I had never even thought of putting FileTime in Get-Date before. That’s why I was surprised. Good Night, my filetime is already near the morning.