DaylightTime Class
Defines the period of daylight saving time.
Assembly: mscorlib (in mscorlib.dll)
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
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