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TimeZoneInfo.TransitionTime F# snippets (#7916)
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‎snippets/fsharp/System/TimeZoneInfo+TransitionTime/CreateFixedDateRule/System.TimeZone2.TransitionTime.Class.fs‎

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module Program
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open System
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open System.Globalization
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let compareForEquality () =
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// <Snippet1>
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let tt1 = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 02, 00, 00), 11, 03)
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let tt2 = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 02, 00, 00), 11, 03)
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let tt3 = TimeZoneInfo.TransitionTime.CreateFloatingDateRule(DateTime(1, 1, 1, 02, 00, 00), 10, 05, DayOfWeek.Sunday)
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let tz = TimeZoneInfo.Local
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printfn $"{tt1.Equals tz}" // Returns False (overload with argument of type Object)
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printfn $"{tt1.Equals tt1}" // Returns True (an object always equals itself)
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printfn $"{tt1.Equals tt2}" // Returns True (identical property values)
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printfn $"{tt1.Equals tt3}" // Returns False (different property values)
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// </Snippet1>
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let compareTransitionTimesForEquality () =
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// <Snippet7>
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let tt1 = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 02, 00, 00), 11, 03)
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let tt2 = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 02, 00, 00), 11, 03)
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let tt3 = TimeZoneInfo.TransitionTime.CreateFloatingDateRule(DateTime(1, 1, 1, 02, 00, 00), 10, 05, DayOfWeek.Sunday)
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printfn $"{tt1.Equals tt1}" // Returns True (an object always equals itself)
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printfn $"{tt1.Equals tt2}" // Returns True (identical property values)
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printfn $"{tt1.Equals tt3}" // Returns False (different property values)
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// </Snippet7>
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let createTransitionRules () =
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// <Snippet2>
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let delta = TimeSpan(1, 0, 0)
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let adjustmentList = ResizeArray()
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// Define a fictitious new time zone consisting of fixed and floating adjustment rules
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// Define fixed rule (for 1900-1955)
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let transitionRuleStart = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 2, 0, 0), 3, 15)
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let transitionRuleEnd = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 3, 0, 0), 11, 15)
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let adjustment =
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TimeZoneInfo.AdjustmentRule.CreateAdjustmentRule(DateTime(1900, 1, 1), DateTime(1955, 12, 31), delta, transitionRuleStart, transitionRuleEnd)
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adjustmentList.Add adjustment
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// Define floating rule (for 1956- )
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let transitionRuleStart = TimeZoneInfo.TransitionTime.CreateFloatingDateRule(DateTime(1, 1, 1, 2, 0, 0), 3, 5, DayOfWeek.Sunday)
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let transitionRuleEnd = TimeZoneInfo.TransitionTime.CreateFloatingDateRule(DateTime(1, 1, 1, 3, 0, 0), 10, 4, DayOfWeek.Sunday)
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let adjustment = TimeZoneInfo.AdjustmentRule.CreateAdjustmentRule(DateTime(1956, 1, 1), DateTime.MaxValue.Date, delta, transitionRuleStart, transitionRuleEnd)
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adjustmentList.Add adjustment
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// Create fictitious time zone
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let imaginaryTZ =
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TimeZoneInfo.CreateCustomTimeZone("Fictitious Standard Time", TimeSpan(-9, 0, 0),
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"(GMT-09:00) Fictitious Time", "Fictitious Standard Time",
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"Fictitious Daylight Time", adjustmentList.ToArray())
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// </Snippet2>
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()
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// <Snippet3>
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let getFixedTransitionTimes () =
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let timeZones = TimeZoneInfo.GetSystemTimeZones()
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let dateInfo = CultureInfo.CurrentCulture.DateTimeFormat
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for zone in timeZones do
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let adjustmentRules = zone.GetAdjustmentRules()
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for adjustmentRule in adjustmentRules do
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let daylightStart = adjustmentRule.DaylightTransitionStart
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if daylightStart.IsFixedDateRule then
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printfn $"For {zone.StandardName}, daylight savings time begins at {daylightStart.TimeOfDay:t} on {dateInfo.GetMonthName daylightStart.Month} {daylightStart.Day} from {adjustmentRule.DateStart:d} to {adjustmentRule.DateEnd:d}."
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let daylightEnd = adjustmentRule.DaylightTransitionEnd
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if daylightEnd.IsFixedDateRule then
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printfn $"For {zone.StandardName}, daylight savings time ends at {daylightEnd.TimeOfDay:t} on {dateInfo.GetMonthName daylightEnd.Month} {daylightEnd.Day} from {adjustmentRule.DateStart:d} to {adjustmentRule.DateEnd:d}."
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// </Snippet3>
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// <Snippet4>
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type WeekOfMonth =
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| First = 1
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| Second = 2
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| Third = 3
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| Fourth = 4
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| Last = 5
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let getFloatingTransitionTimes () =
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let timeZones = TimeZoneInfo.GetSystemTimeZones()
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for zone in timeZones do
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let adjustmentRules = zone.GetAdjustmentRules()
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let dateInfo = CultureInfo.CurrentCulture.DateTimeFormat
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for adjustmentRule in adjustmentRules do
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let daylightStart = adjustmentRule.DaylightTransitionStart
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if not daylightStart.IsFixedDateRule then
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printfn $"{zone.StandardName}, {adjustmentRule.DateStart:d}-{adjustmentRule.DateEnd:d}: Begins at {daylightStart.TimeOfDay:t} on the {enum<WeekOfMonth> daylightStart.Week} {daylightStart.DayOfWeek} of {dateInfo.GetMonthName daylightStart.Month}."
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let daylightEnd = adjustmentRule.DaylightTransitionEnd
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if not daylightEnd.IsFixedDateRule then
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printfn $"{zone.StandardName}, {adjustmentRule.DateStart:d}-{adjustmentRule.DateEnd:d}: Ends at {daylightEnd.TimeOfDay:t} on the {enum<WeekOfMonth> daylightEnd.Week} {daylightEnd.DayOfWeek} of {dateInfo.GetMonthName daylightEnd.Month}."
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// </Snippet4>
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module AdditionalExamples =
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// <Snippet6>
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type WeekOfMonth =
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| First = 1
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| Second = 2
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| Third = 3
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| Fourth = 4
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| Last = 5
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let getAllTransitionTimes () =
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let timeZones = TimeZoneInfo.GetSystemTimeZones()
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let dateInfo = CultureInfo.CurrentCulture.DateTimeFormat
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for zone in timeZones do
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printfn $"{zone.StandardName} transition time information:"
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let adjustmentRules= zone.GetAdjustmentRules()
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// Indicate that time zone has no adjustment rules
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if adjustmentRules.Length = 0 then
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printfn " No adjustment rules defined."
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else
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// Iterate adjustment rules
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for adjustmentRule in adjustmentRules do
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printfn $" Adjustment rule from {adjustmentRule.DateStart:d} to {adjustmentRule.DateEnd:d}:"
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// Get start of transition
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let daylightStart = adjustmentRule.DaylightTransitionStart
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// Display information on fixed date rule
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if not daylightStart.IsFixedDateRule then
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printfn $" Begins at {daylightStart.TimeOfDay:t} on the {enum<WeekOfMonth> daylightStart.Week} {daylightStart.DayOfWeek} of {dateInfo.GetMonthName daylightStart.Month}."
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// Display information on floating date rule
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else
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printfn $" Begins at {daylightStart.TimeOfDay:t} on the {enum<WeekOfMonth> daylightStart.Week} {daylightStart.DayOfWeek} of {dateInfo.GetMonthName daylightStart.Month}."
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// Get end of transition
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let daylightEnd = adjustmentRule.DaylightTransitionEnd
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// Display information on fixed date rule
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if not daylightEnd.IsFixedDateRule then
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printfn $" Ends at {daylightEnd.TimeOfDay:t} on the {enum<WeekOfMonth> daylightEnd.Week} {daylightEnd.DayOfWeek} of {dateInfo.GetMonthName daylightEnd.Month}."
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// Display information on floating date rule
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else
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printfn $" Ends at {daylightStart.TimeOfDay:t} on the {enum<WeekOfMonth> daylightStart.Week} {daylightStart.DayOfWeek} of {dateInfo.GetMonthName daylightStart.Month}."
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// </Snippet6>
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compareForEquality ()
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printfn ""
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compareTransitionTimesForEquality()
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printfn ""
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createTransitionRules()
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printfn ""
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getFixedTransitionTimes ()
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printfn ""
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getFloatingTransitionTimes ()
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printfn ""
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AdditionalExamples.getAllTransitionTimes ()

‎snippets/fsharp/System/TimeZoneInfo+TransitionTime/CreateFixedDateRule/example1.fs‎

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module example1
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// <Snippet5>
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open System
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open System.Globalization
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let displayTransitionInfo (transition: TimeZoneInfo.TransitionTime) year label =
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// For non-fixed date rules, get local calendar
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let cal = CultureInfo.CurrentCulture.Calendar
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// Get first day of week for transition
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// For example, the 3rd week starts no earlier than the 15th of the month
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let startOfWeek = transition.Week * 7 - 6
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// What day of the week does the month start on?
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let firstDayOfWeek = cal.GetDayOfWeek(DateTime(year, transition.Month, 1)) |> int
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// Determine how much start date has to be adjusted
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let changeDayOfWeek = int transition.DayOfWeek
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let transitionDay =
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if firstDayOfWeek <= changeDayOfWeek then
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startOfWeek + (changeDayOfWeek - firstDayOfWeek)
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else
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startOfWeek + (7 - firstDayOfWeek + changeDayOfWeek)
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// Adjust for months with no fifth week
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let transitionDay =
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if transitionDay > cal.GetDaysInMonth(year, transition.Month) then
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transitionDay - 7
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else
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transitionDay
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printfn $" {label} {transition.DayOfWeek}, {DateTime(year, transition.Month, transitionDay):d} at {transition.TimeOfDay:t}"
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let getAdjustment (adjustments: TimeZoneInfo.AdjustmentRule seq) year =
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adjustments
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// Iterate adjustment rules for time zone
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// Determine if this adjustment rule covers year desired
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|> Seq.tryFind (fun adjustment -> adjustment.DateStart.Year <= year && adjustment.DateEnd >= DateTime year)
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|> Option.defaultValue null
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let getTransitionTimes year =
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// Instantiate DateTimeFormatInfo object for month names
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let dateFormat = CultureInfo.CurrentCulture.DateTimeFormat
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// Get and iterate time zones on local computer
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let timeZones = TimeZoneInfo.GetSystemTimeZones()
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for timeZone in timeZones do
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printfn $"{timeZone.StandardName}:"
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let adjustments = timeZone.GetAdjustmentRules()
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let startYear = year
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let mutable endYear = startYear
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if adjustments.Length = 0 then
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printfn " No adjustment rules."
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else
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let adjustment = getAdjustment adjustments year
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if adjustment = null then
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Console.WriteLine(" No adjustment rules available for this year.")
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else
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// Determine if starting transition is fixed
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let startTransition = adjustment.DaylightTransitionStart
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// Determine if starting transition is fixed and display transition info for year
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if startTransition.IsFixedDateRule then
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printfn $" Begins on {dateFormat.GetMonthName startTransition.Month} {startTransition.Day} at {startTransition.TimeOfDay:t}"
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else
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displayTransitionInfo startTransition startYear "Begins on"
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// Determine if ending transition is fixed and display transition info for year
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let mutable endTransition = adjustment.DaylightTransitionEnd
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// Does the transition back occur in an earlier month (i.e.,
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// the following year) than the transition to DST? If so, make
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// sure we have the right adjustment rule.
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if endTransition.Month < startTransition.Month then
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endTransition <- (getAdjustment adjustments (year + 1)).DaylightTransitionEnd
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endYear <- endYear + 1
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if endTransition.IsFixedDateRule then
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printfn $" Ends on {dateFormat.GetMonthName endTransition.Month} {endTransition.Day} at {endTransition.TimeOfDay:t}"
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else
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displayTransitionInfo endTransition endYear "Ends on"
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// </Snippet5>
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getTransitionTimes 2007

‎snippets/fsharp/System/TimeZoneInfo+TransitionTime/CreateFixedDateRule/fs.fsproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net6.0</TargetFramework>
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</PropertyGroup>
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<ItemGroup>
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<Compile Include="example1.fs" />
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<Compile Include="System.TimeZone2.TransitionTime.Class.fs" />
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</ItemGroup>
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</Project>

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