DateTime: strange behaviour

PowerShell Help
1

Hello,

this is a simple affair. However the outcome surprises me and perhaps s.b. can explain.
I define a string $myDate.
In the beginning the data has three dashes.
I consider this as incorrect. However, it goes through as a correct date. Why?

Also I don’t seem to be able to output the date at will in english or in German.
$date.ToString() outside write-host comes out in German.
The variable $date inside write-host turns out in english.

I would want to know how exactly can I set it to one or the other language using the same programming?
Here the code:

#Set-Culture en-US
$Culture = New-Object System.Globalization.CultureInfo("en-US")
# $culture=[cultureInfo]'en-US'
$myDate = "2025-05-02-13 11:01"
$result= $myDate-as [DateTime] -ne $null
write-host
write-host "`$result evaluates as $result"
$date = get-date "$myDate" -Format ($culture.DateTimeFormat.LongDateTimePattern)
write-host "The date in German = " $date.ToString()
write-host "Date in english = $date"
$date
2

Hi,
I can just convert $date to a string and specify the culture:
$date.tostring($Culture) # will come out in english

But why is the date with three dashes counted on to the third of may instead of throwing an error?

3

The DateTime parser in dotNet accepts datetime strings with ’ ', ‘.’ or ‘-’ as acceptable date separators. There may be others…

4

Hi,
thank you for responding.
I am aware that you can use comma as well as dash for date separation.
However, normally a space separates the actual date from the time.
So I would expect two dashes as acceptable in a date - separating month from day and year from month.
A third dash is senseless, isn’t it?
But somehow powershell accepts it and takes it for hours and counts the days up.
This shouldn’t be and forces me to use

[datetime::ParseExact($date,"dd.MM.yyyy HH:mm",$null)

Had the treatment of the $date not been muddled up here, I had liked to use:

if ([string]$date -as [DateTime])

Regards

Andreas

5

I am concerned about first checking for a correct date and I do not want s.b. who uses my script to be able to enter a date with three dashes. But as Powershell would incorrectly allow him to do just that I have to check otherwise.

6

Also you can see in ParseExact that the design actually is two dashes in the date (and not three) and then a space that separates time from date.

7

Well I used a dot, but you could replace it with a dash.

8

If you depend on user input you should always validate the input. A great way to avoid invalid input is to limit the choice you give the user. In a case like this case you could use a date picker and if really needed a time picker.

9

Hi,
I am an administrator. But the only one who (can write) writes those scripts.
My colleagues are not normal users but also administrators. They open the script and change the date.
For them, I don’t need a picker.
However, being inattentive a third dash could slip in, which I don’t want.

10

three dashes in the date part, to me seems to be a bug in powershell.

11

IMHO that’s not a good idea anyway … even if they are admins as well. How about using parameters for the needed input? I’d expect that to be way less error prone.

12

You may file a bug report. :point_up: :man_shrugging:

13

Of course they only change the parameter and not code.
After they change the parameter I check whether the parameter has a correct date.
And I do not want a parameter with three dashes where the day is then counted up, even though Powershell would accept it.