Examples of time difference calculations (between now and an arbitrary future date) and other date and time related tasks in Windows PowerShell.

Get-TimeDifference.ps1

<#
Get-TimeDifference.ps1

Windows PowerShell: For a more comfortable reading experience, please type
help ./Get-TimeDifference -Full
#>




<#

.SYNOPSIS
Examples of time difference calculations (between now and an arbitrary future date)
and other date and time related tasks in Windows PowerShell.

.DESCRIPTION
The script will not output anything. Please type
help ./Get-TimeDifference -Full
to see the included date and time related examples.

.EXAMPLE

(Get-Date -year 2099 -month 1 -day 1 -hour 0 -minute 0 -second 0) - (Get-Date)

This example calculates the time difference between the time that the command is
run and the start of the year 2099 in the Gregorian calendar (January 1, 2099 at
00:00:00 hours). The output is always the same regardles of the current locale
settings.


            Days : 30086
            Hours : 4
            Minutes : 10
            Seconds : 36
            Milliseconds : 0
            Ticks : 25994454360000000
            TotalDays : 30086,1740277778
            TotalHours : 722068,176666667
            TotalMinutes : 43324090,6
            TotalSeconds : 2599445436
            TotalMilliseconds : 2599445436000

            Universal = $true


.EXAMPLE

New-TimeSpan -End (Get-Date -year 2099 -month 1 -day 1 -hour 0 -minute 0 -second 0)

In this example a new TimeSpan object is created that represents the aforementioned
time interval. The command does not require the -Start parameter, because the default
value of the -Start parameter in New-TimeSpan is the current date and time. The
output is always the same regardles of the current locale settings.


            Days : 30086
            Hours : 4
            Minutes : 10
            Seconds : 36
            Milliseconds : 0
            Ticks : 25994454360000000
            TotalDays : 30086,1740277778
            TotalHours : 722068,176666667
            TotalMinutes : 43324090,6
            TotalSeconds : 2599445436
            TotalMilliseconds : 2599445436000

            Universal = $true


.EXAMPLE

(Get-Date) + (New-TimeSpan -days 90)

This command returns the date that is 90 days after the current date and displays
it in the default date and time format, which depends on the current locale setting,
so the output is not universal, but varies according to the prevalent settings.


            Default Locale: Friday, June 16, 2006 10:31:27 AM

            Universal = $false


.EXAMPLE

Get-Date -Format g

This command retrieves the current date and time and formats it in short-date
and short-time format according to the current locale settings. It uses the .NET 
Framework "g" format specifier (General [short date and short time]) to
specify the format.


            Locale 1: 13.6.2006 12:46
            Locale 2: 6/13/2006 12:46 PM

            Universal = $false


.EXAMPLE

Get-Date -Format HH:mm:ss

This command retrieves a 24-hour timestamp that is in the 24-hour format regardles
of the current locale settings, so the output is universally always the same.


            17:13:03

            Universal = $true


.EXAMPLE

(Get-Date).ToUniversalTime()

This command converts the current date and time to UTC time and displays it in the
format that is specified in the locale settings, so that for example, the name of
the month name is translated to the language that the computer is using.


            Tuesday, June 13, 2006 8:09:19 PM

            UniversalTime = $true
            'UniversalTime (UTC)' = $true
            'Universal Date and Time Display Format' = $false
            'Local Time' =  If ( $LocalTime -eq $UniversalTimeUTC ) { 
                                $true 
                            } Else { 
                                $false 
                            } # else


.EXAMPLE

Get-Date ((Get-Date).ToUniversalTime()) -Format HH:mm:ss

This command converts the current time to UTC time and displays it in the
24-hour format regardles of the current locale settings, so the output is 
universally always the same. 


            16:18:46

            Universal = $true
            UniversalTime = $true
            'UniversalTime (UTC)' = $true
            'Universal Date and Time Display Format' = $true
            'Local Time' =  If ( $LocalTime -eq $UniversalTimeUTC ) { 
                                $true 
                            } Else { 
                                $false 
                            } # else


.EXAMPLE

Get-WmiObject -Class Win32_BIOS -ComputerName $env:COMPUTERNAME | Format-List -property Name, @{Label="BIOS Age"; Expression={ [string]((Get-Date) - $_.ConvertToDateTime($_.ReleaseDate)).Days + ' Days' }}

Windows Management Instrumentation (WMI) uses a different date-time object than the .NET 
Framework date-time object that Get-Date returns. To use date-time information 
from WMI in a command with date-time information from Get-Date, ConvertToDateTime 
method could be used to convert WMI CIM_DATETIME objects to .NET Framework DateTime 
objects.

In this example the name and age of the BIOS of the computer is displayed in days.
The output is always the same regardles of the current locale settings.


            Name     : Default System BIOS
            BIOS Age : 345 Days

            Universal = $true


.EXAMPLE

(Get-Date).IsDaylightSavingTime()

This command tells, whether the current date and time are adjusted for daylight 
savings time in the current locale and returns True or False accordingly. The 
format of the output is always the same regardles of the current locale settings.


            True / False

            Result = If ( ($LocalDateAndTime -ge $StartOfTheDaylightSavingTimeInCurrentYear) -and ($LocalDateAndTime -lt $EndOfTheDaylightSavingTimeInCurrentYear) ) { 
                                'True' 
                            } Else { 
                                'False' 
                            } # else

            Universal = $true
            UniversalOutputFormat = $true
            UniversalResults = $false


.LINK
Get-Date: http://go.microsoft.com/fwlink/?LinkID=113313
New-TimeSpan: http://go.microsoft.com/fwlink/?LinkID=113360

#>

Days : 30086
Hours : 4
Minutes : 10
Seconds : 36
Milliseconds : 0
Ticks : 25994454360000000
TotalDays : 30086,1740277778
TotalHours : 722068,176666667
TotalMinutes : 43324090,6
TotalSeconds : 2599445436
TotalMilliseconds : 2599445436000