Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All

DaylightTime Class

Defines the period of daylight saving time.

Namespace:  System.Globalization
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public Class DaylightTime
'Usage
Dim instance As DaylightTime

Daylight saving time is a period during the year when the time is advanced, usually by an hour, to take advantage of the extended daylight hours. At the end of the period, the time is set back to the standard time.

The DaylightTime class is used extensively by members of the System.TimeZone class.

The following code example uses the TimeZone.GetDaylightChanges(Int32) method to return the daylight saving time period and offset for selected years.

' Example of the TimeZone.GetDaylightChanges( Integer ) method. 
Imports System
Imports System.Globalization
Imports Microsoft.VisualBasic

Module DaylightChangesDemo

    ' Get the local time zone and a base local time. 
    Dim localZone As TimeZone = TimeZone.CurrentTimeZone

    Sub CreateDaylightTime( year As Integer )

        ' Create a DaylightTime object for the specified year. 
        Dim daylight As DaylightTime = _
            localZone.GetDaylightChanges( year )

        ' Display the start and end dates and the time change.
        Console.WriteLine( "{0,-7}{1,-20:yyyy-MM-dd HH:mm}" & _
            "{2,-20:yyyy-MM-dd HH:mm}{3}", _
            year, daylight.Start, daylight.End, daylight.Delta )
    End Sub  

    Sub Main( )

        Const headFmt As String = "{0,-7}{1,-20}{2,-20}{3}"

        Console.WriteLine( _
            "This example of TimeZone.GetDaylightChanges( " & _
            "Integer ) generates the " & vbCrLf & "following " & _
            "output, which varies depending on the time zone " & _
            "in which " & vbCrLf & "it is run. The example " & _
            "creates DaylightTime objects for specified " & _
            vbCrLf & "years and displays the start and end dates " & _
            "and time change for " & vbCrLf &  "daylight " & _
            "saving time." & vbCrLf )

        ' Write a message explaining that start dates prior to 1986  
        ' in the en-US culture may not be correct. 
        If CultureInfo.CurrentCulture.Name = "en-US" Then

            Console.WriteLine( _
                "Note: In the [en-US] culture, all start dates " & _
                "are calculated from " & vbCrLf & "the first " & _
                "Sunday in April, based on a standard set in " & _
                "1986. For " & vbCrLf & "dates prior to 1986, " & _
                "the calculated start date may not be accurate." )
        End If

        Console.WriteLine( vbCrLf & "Local time: {0}" & vbCrLf, _
            localZone.StandardName )

        Console.WriteLine( headFmt, "Year", "Start", "End", "Change" )
        Console.WriteLine( headFmt, "----", "-----", "---", "------" )

        CreateDaylightTime( 1960 )
        CreateDaylightTime( 1970 )
        CreateDaylightTime( 1980 )
        CreateDaylightTime( 1990 )
        CreateDaylightTime( 2000 )
        CreateDaylightTime( 2001 )
        CreateDaylightTime( 2002 )
        CreateDaylightTime( 2003 )
        CreateDaylightTime( 2004 )
        CreateDaylightTime( 2005 )
        CreateDaylightTime( 2020 )
        CreateDaylightTime( 2040 )
    End Sub  
End Module  

' This example of TimeZone.GetDaylightChanges( Integer ) generates the 
' following output, which varies depending on the time zone in which 
' it is run. The example creates DaylightTime objects for specified 
' years and displays the start and end dates and time change for 
' daylight saving time. 
'  
' Note: In the [en-US] culture, all start dates are calculated from 
' the first Sunday in April, based on a standard set in 1986. For 
' dates prior to 1986, the calculated start date may not be accurate. 
'  
' Local time: Pacific Standard Time 
'  
' Year   Start               End                 Change 
' ----   -----               ---                 ------ 
' 1960   1960-04-03 02:00    1960-10-30 02:00    01:00:00 
' 1970   1970-04-05 02:00    1970-10-25 02:00    01:00:00 
' 1980   1980-04-06 02:00    1980-10-26 02:00    01:00:00 
' 1990   1990-04-01 02:00    1990-10-28 02:00    01:00:00 
' 2000   2000-04-02 02:00    2000-10-29 02:00    01:00:00 
' 2001   2001-04-01 02:00    2001-10-28 02:00    01:00:00 
' 2002   2002-04-07 02:00    2002-10-27 02:00    01:00:00 
' 2003   2003-04-06 02:00    2003-10-26 02:00    01:00:00 
' 2004   2004-04-04 02:00    2004-10-31 02:00    01:00:00 
' 2005   2005-04-03 02:00    2005-10-30 02:00    01:00:00 
' 2020   2020-04-05 02:00    2020-10-25 02:00    01:00:00 
' 2040   2040-04-01 02:00    2040-10-28 02:00    01:00:00

System.Object
  System.Globalization.DaylightTime

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Community Additions

ADD
Show:
© 2015 Microsoft