Datetime in PowerShell can't convert my Time - powershell

Question

I'm writing a Script to compare two sets of timevalues and then calculate a exact time.
My problem is the calculation with timestamps. I import the times from a .csv-file. The times look like this:
08:37;
11:47;
12:11;
17:34;
etc.
I made a variable for the times so i always have the correct time from the correct line from the csv file.
My goal ist to calculate the time from one timestamp to another like this: 11:47 - 08:37 = 3:10
If i do this in my PowerShell Script an error occurs: The value "time=12:39" can not be converted to type "System.DateTime". Error: "The string was not recognized as a DateTime. An unknown word starts at index 1"
Is datetime wrong in this case? How can i make this work?
Thx for your help.

Answer 1

If this has to do with your previous question and the CSV actually looks like this:
name;prename;date;time
Gantz;Mario;09.02.;07:37
Gantz;Mario;09.02.;11:23
Gantz;Mario;09.02.;12:34
Gantz;Mario;09.02.;17:03
Then this should do it
# create two variables to hold the times parsed from the CSV, Initialize to $null
$current, $previous = $null
# load the csv and loop through the records
$result = Import-Csv -Path 'D:\Test\times.csv' -Delimiter ';' | ForEach-Object {
$current = [datetime]::ParseExact($_.time, 'HH:mm', $null)
if (!$previous) { $previous = $current }
# subtracting two DateTime objects results in a TimeStamp
$elapsed = $current - $previous
$previous = $current
# output the record with column 'elapsed' appended
$_ | Select-Object *, #{Name = 'elapsed'; Expression = {$elapsed.ToString()}}
}
# output on screen
$result | Format-Table -AutoSize
# output to new CSV file
$result | Export-Csv -Path 'D:\Test\times_and_intervals.csv' -Delimiter ';' -NoTypeInformation
Output on screen:
name prename date time elapsed
---- ------- ---- ---- -------
Gantz Mario 09.02. 07:37 00:00:00
Gantz Mario 09.02. 11:23 03:46:00
Gantz Mario 09.02. 12:34 01:11:00
Gantz Mario 09.02. 17:03 04:29:00
Now that I see you also have a 'date' column in there, you should include that in the conversion to [datetime] aswell:
# create two variables to hold the times parsed from the CSV, Initialize to $null
$current, $previous = $null
# load the csv and loop through the records
$result = Import-Csv -Path 'D:\Test\times.csv' -Delimiter ';' | ForEach-Object {
$completeDate = '{0}{1} {2}' -f $_.date, (Get-Date).Year, $_.time
$current = [datetime]::ParseExact($completeDate, 'dd.MM.yyyy HH:mm', $null)
if (!$previous) { $previous = $current }
# subtracting two DateTime objects results in a TimeStamp
$elapsed = $current - $previous
$previous = $current
# output the record with column 'elapsed' appended
$_ | Select-Object *, #{Name = 'elapsed'; Expression = {$elapsed.ToString()}}
}
# output on screen
$result | Format-Table -AutoSize
# output to new CSV file
$result | Export-Csv -Path 'D:\Test\times_and_intervals.csv' -Delimiter ';' -NoTypeInformation

Answer 2

You are getting the error because you are not specifying the values that you are importing as [datetime]
I have replicated the error where I just specified 2 time values and subtracted them:
$st = "08:37" $et = "11:47" $di = $st - $et Cannot convert value
"08:37" to type "System.Int32". Error: "Input string was not in a
correct format."
Solution:
Specify the values of each entry like so:
[datetime]$starttime = "08:37"
[datetime]$endtime = "11:47"
$diff = $endtime - $starttime
If you just want the time in minutes etc. you can enter $diff.Minutes respectively
Hope this works for you.