CODEWITHSUNDEEP
powershell
Karan
Karan

Reputation: 711

Getting the # of days difference between two dates in Powershell

I am trying to get the number of days difference in Windows powershell, I am extracting the last date of the year i.e.. 20171231(yyyyMMdd) from a text file that I have locally stored the date in that file.

Here is the below code that I am trying but not able to get the difference of the days, am getting the wrong output by directly subtracting, if am converting the string extracted from the file and then subtract it with the date type, even then am getting the wrong output.

$DateStr = (Get-Date).ToString("yyyyMMdd")

$content = Get-Content C:\Users\Date.txt 

$diff = $content.ToString();

#Convert it to the date type
$diff = [datetime]::parseexact($diff, 'yyyyMMdd', $null)

#$diff3 = $diff - $DateStr

Upvotes: 31

Views: 102598

Answers (7)

Mike Q
Mike Q

Reputation: 7327

Explaination

We can use floor or ceiling to get the full number of days between two dates, if you want to round it up or down use [math]::Round instead.

Example:

As a Positive Value:

$pastDate = (Get-Date).AddDays(-44.9)     
[math]::Floor(((Get-Date) - $pastDate).TotalDays)
44

As a Negative Value:

$pastDate = (Get-Date).AddDays(-44.9) 
[math]::Ceiling(($pastDate-(Get-Date)).TotalDays)
-44

Upvotes: 1

Eddie Kumar
Eddie Kumar

Reputation: 1480

Great answers by others but I often use Date-Diff function (it's powerful and well known to developers). See example below:

Using Namespace Microsoft.VisualBasic
Add-Type  -AssemblyName  Microsoft.VisualBasic
$start = Get-Date '2019-01-01'  #Convert string into Date type.
$end = Get-Date
[DateAndTime]::DateDiff([DateInterval]::Day, $start, $end)

Edit: Apparently, the new version of PowerShell will support .NET 7, in which case, you won't need to even add assembly.

HTH

Upvotes: 2

js2010
js2010

Reputation: 27428

If you convert to datetime objects it's pretty straighforward to subtract them and look at the days property. This works with times too.

[datetime]'9/3' - [datetime]'9/1' | % days

2


[datetime]'10:30' - [datetime]'9:30' | % hours

1

Upvotes: 1

kenguil-MSFT
kenguil-MSFT

Reputation: 91

A quick, dirty, one line powershell script to get the difference between current date and any future date:

[math]::Ceiling((([DateTime]'mm-dd-yyyy')-(Get-Date)).TotalDays)

Upvotes: 9

Esperento57
Esperento57

Reputation: 17462

$Date = Get-Date

$diff = Get-Content C:\Users\Date.txt -raw

#Convert it to the date type
$diff = [datetime]::parseexact($diff, 'yyyyMMdd', $null)

#simply difference between dates give you a timespan, take days
($diff - $Date).Day

Upvotes: 0

Anthony Allen
Anthony Allen

Reputation: 31

$DateStr is going to be a string, so it can't be parsed as a date. You can also use new-timespan to get the difference between two dates. 

$Date = Get-Date

$diff = Get-Content C:\Users\Date.txt -raw

#Convert it to the date type
$diff = [datetime]::parseexact($diff, 'yyyyMMdd', $null)

$diff3 = New-TimeSpan -Start $diff -end $Date

#Number of days
$diff3.days

Upvotes: 2

vonPryz
vonPryz

Reputation: 24071

Use New-TimeSpan as it represents a time interval. Like so,

$d1 = '2017-01-01'
$d2 = '2017-05-01'
$ts = New-TimeSpan -Start $d1 -End $d2
$ts.Days # Check results
120

Upvotes: 69

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