I am using PowerShell to try and convert a string to a datetime. It should be easy, right?
I am getting the string from a CSV import, and it comes in the format of Jul-16. I have tried multiple ways of getting it into the format I want which is yyyy-MM-dd and I am currently at the following.
$invoice = $object.'Invoice Month'
$invoice = "01-" + $invoice
$invoice = [datetime]::parseexact($invoice, 'yyyy-MM-dd', $null)
But I get the error:
String was not recognized as a valid DateTime.
Am I missing something?
6 Answers
ParseExact is told the format of the date it is expected to parse, not the format you wish to get out.
$invoice = '01-Jul-16'
[datetime]::parseexact($invoice, 'dd-MMM-yy', $null)
If you then wish to output a date string:
[datetime]::parseexact($invoice, 'dd-MMM-yy', $null).ToString('yyyy-MM-dd')
Chris
You can simply cast strings to DateTime:
[DateTime]"2020-7-16"
or
[DateTime]"Jul-16"
or
$myDate = [DateTime]"Jul-16";
And you can format the resulting DateTime variable by doing something like this:
'{0:yyyy-MM-dd}' -f [DateTime]'Jul-16'
or
([DateTime]"Jul-16").ToString('yyyy-MM-dd')
or
$myDate = [DateTime]"Jul-16";
'{0:yyyy-MM-dd}' -f $myDate
You need to specify the format it already has, in order to parse it:
$InvoiceDate = [datetime]::ParseExact($invoice, "dd-MMM-yy", $null)
Now you can output it in the format you need:
$InvoiceDate.ToString('yyyy-MM-dd')
or
'{0:yyyy-MM-dd}' -f $InvoiceDate
Chris Dents' answer has already covered the OPs' question but seeing as this was the top search on google for PowerShell format string as date I thought I'd give a different string example.
If like me, you get the time string like this 20190720170000.000000+000
An important thing to note is you need to use ToUniversalTime() when using [System.Management.ManagementDateTimeConverter] otherwise you get offset times against your input.
PS Code
cls
Write-Host "This example is for the 24hr clock with HH"
Write-Host "ToUniversalTime() must be used when using [System.Management.ManagementDateTimeConverter]"
$my_date_24hr_time = "20190720170000.000000+000"
$date_format = "yyyy-MM-dd HH:mm"
[System.Management.ManagementDateTimeConverter]::ToDateTime($my_date_24hr_time).ToUniversalTime();
[System.Management.ManagementDateTimeConverter]::ToDateTime($my_date_24hr_time).ToUniversalTime().ToSTring($date_format)
[datetime]::ParseExact($my_date_24hr_time,"yyyyMMddHHmmss.000000+000",$null).ToSTring($date_format)
Write-Host
Write-Host "-----------------------------"
Write-Host
Write-Host "This example is for the am pm clock with hh"
Write-Host "Again, ToUniversalTime() must be used when using [System.Management.ManagementDateTimeConverter]"
Write-Host
$my_date_ampm_time = "20190720110000.000000+000"
[System.Management.ManagementDateTimeConverter]::ToDateTime($my_date_ampm_time).ToUniversalTime();
[System.Management.ManagementDateTimeConverter]::ToDateTime($my_date_ampm_time).ToUniversalTime().ToSTring($date_format)
[datetime]::ParseExact($my_date_ampm_time,"yyyyMMddhhmmss.000000+000",$null).ToSTring($date_format)
