PowerShell get latest string date

Question

I have a list with dates inside

$date = @('05-28-2020','09-30-2021')

I want to find the most recent date

I tried to convert string before comparat it:

[datetime]::ParseExact($date[0],'MM_dd_yyyy', $null)

But not working

Any ideas?

Answer 1

• You can directly cast your date-time strings to [datetime] - no need for a ParseExact() call - given that your input format is recognized by the invariant culture that PowerShell always uses in casts.

• System.Linq.Enumerable.Max<T>() allows you to find the maximum in a [datetime] -typed enumerable.

Therefore:

$date = @('05-28-2020','09-30-2021') # Note: The @(...) enclosure isn't strictly needed.

[Linq.Enumerable]::Max([datetime[]] $date)

On a US-English system, the above yields Thursday, September 30, 2021 12:00:00 AM , ie the default output formatting of the most recent date in the input, [datetime] '09-30-2021' .

---

As for what you tried :

• As has been mentioned, the only immediate problem with your ParseExact() call was that you used _ instead of - .

• Also note that passing $null as the third argument implies that the culture currently in effect is used during parsing (as reflected in [cultureinfo]::CurrentCulture ; this won't matter with numeric formatting sequences such as MM , but it would with symbolic ones such as MMM - and potentially even with unquoted placeholders : and / .

Answer 2

switch your _ to - and it will work:

Answer 3

$date = @('05-28-2020','09-30-2021')
$max = '01-01-1999'
$date | ForEach-Object {
    if($_ -ge $max){
        $max = $_
    }
}

This should do the work.