IsDayLightSavingTime doesn't work for 2007 and beyond

[vCharley Lee]

Is this going to be patched? I ran this code and it fails to report the
correct state of Daylight Savings Time in Pacific Time zone. March 12, 2007
should be DST.

Thanks,

Charley

' Example of the TimeZone.IsDaylightSavingTime( DateTime ),
' TimeZone.IsDaylightSavingTime( DateTime, DaylightTime ), and
' TimeZone.ToUniversalTime( DateTime ) methods.
Imports System
Imports System.Globalization
Imports Microsoft.VisualBasic

Module DaylightTimeDemo

Sub Main()

Const headFmt As String = "{0,-22}{1,-10}{2,-10}{3,-10}{4}"

' Get the local time zone and a base local time.
Dim localZone As TimeZone = TimeZone.CurrentTimeZone
Dim localTime As DateTime = New DateTime(2007, 3, 12)

Console.WriteLine("This example of " & vbCrLf & _
" TimeZone.IsDaylightSavingTime( DateTime ), " & _
vbCrLf & " TimeZone.IsDaylightSavingTime( " & _
"DateTime, DaylightTime ), and " & vbCrLf & _
" TimeZone.ToUniversalTime( DateTime )" & vbCrLf & _
"generates the following output, which varies " & _
"depending on the " & vbCrLf & "time zone in which " & _
"it is run." & vbCrLf)
Console.WriteLine("The example creates " & _
"several local times and the corresponding " & vbCrLf & _
"Coordinated Universal Times (UTC) and shows if " & _
"they occur in " & vbCrLf & "daylight saving time " & _
"(DST), both for specified years and for " & vbCrLf & _
"any year." & vbCrLf)
Console.WriteLine("Local time: {0}" & vbCrLf, _
localZone.StandardName)

Console.WriteLine(headFmt, "Local Date and Time", _
"2001 DST?", "2002 DST?", "Any DST?", "Corresponding UTC")
Console.WriteLine(headFmt, "-------------------", _
"---------", "---------", "--------", "-----------------")

' Create DaylightTime objects for specific years.
Dim daylight2001 As DaylightTime = _
localZone.GetDaylightChanges(2001)
Dim daylight2002 As DaylightTime = _
localZone.GetDaylightChanges(2002)

' Generate several local times.
Dim loopX As Integer
For loopX = 0 To 10

' Calculate the corresponding UTC.
Dim utcTime As DateTime = _
localZone.ToUniversalTime(localTime)

' Show if dates and times occur in daylight saving
' time, for specified years and for any year.
Console.WriteLine("{0,-22:yyyy-MM-dd HH:mm}" & _
"{1,-10}{2,-10}{3,-10}{4:yyyy-MM-dd HH:mm}", _
localTime, _
TimeZone.IsDaylightSavingTime( _
localTime, daylight2001), _
TimeZone.IsDaylightSavingTime( _
localTime, daylight2002), _
localZone.IsDaylightSavingTime(localTime), _
utcTime)

' Advance to another local time.
localTime = localTime.AddDays(109.1)
Next loopX
Threading.Thread.Sleep(60000)
End Sub
End Module

' This example of
' TimeZone.IsDaylightSavingTime( DateTime ),
' TimeZone.IsDaylightSavingTime( DateTime, DaylightTime ), and
' TimeZone.ToUniversalTime( DateTime )
' generates the following output, which varies depending on the
' time zone in which it is run.
'
' The example creates several local times and the corresponding
' Coordinated Universal Times (UTC) and shows if they occur in
' daylight saving time (DST), both for specified years and for
' any year.
'
' Local time: Pacific Standard Time
'
' Local Date and Time 2001 DST? 2002 DST? Any DST? Corresponding UTC
' ------------------- --------- --------- -------- -----------------
' 2001-01-01 00:00 False False False 2001-01-01 08:00
' 2001-04-20 02:24 True False True 2001-04-20 09:24
' 2001-08-07 04:48 True False True 2001-08-07 11:48
' 2001-11-24 07:12 False False False 2001-11-24 15:12
' 2002-03-13 09:36 False False False 2002-03-13 17:36
' 2002-06-30 12:00 False True True 2002-06-30 19:00
' 2002-10-17 14:24 False True True 2002-10-17 21:24
' 2003-02-03 16:48 False False False 2003-02-04 00:48
' 2003-05-23 19:12 False False True 2003-05-24 02:12
' 2003-09-09 21:36 False False True 2003-09-10 04:36
' 2003-12-28 00:00 False False False 2003-12-28 08:00

 

[Michael D. Ober]

This is a change to the US DST laws. MS (and just about every other OS and
tool vendor) will need to issue several patches for this one.

Mike Ober.

 

[vCharley Lee]

So does anyone know how this will be distributed? Simply a hotfix/patch or
in a service pack? Is there an official response from MS?

Thanks,

Charley Lee
Russell Investment Group
Senior Software Developer

 

[Michael D. Ober]

Probably on Patch Tuesday. MS had to send out a similar patch for Australia
this year.

Mike.