How to use DateOnly and TimeOnly (2023)

TheDateOnlyandTimeOnlystructures were introduced with .NET 6 and represent a specific date or time-of-day, respectively. Prior to .NET 6, and always in .NET Framework, developers used theDateTimetype (or some other alternative) to represent one of the following:

• A whole date and time.
• A date, disregarding the time.
• A time, disregarding the date.

DateOnlyandTimeOnlyare types that represent those particular portions of aDateTimetype.

The DateOnly structure

TheDateOnlystructure represents a specific date, without time. Since it has no time component, it represents a date from the start of the day to the end of the day. This structure is ideal for storing specific dates, such as a birth date, an anniversary date, or business-related dates.

Although you could useDateTimewhile ignoring the time component, there are a few benefits to usingDateOnlyoverDateTime:

• TheDateTimestructure may roll into the previous or next day if it's offset by a time zone.DateOnlycan't be offset by a time zone, and it always represents the date that was set.

• Serializing aDateTimestructure includes the time component, which may obscure the intent of the data. Also,DateOnlyserializes less data.

• When code interacts with a database, such as SQL Server, whole dates are generally stored as thedatedata type, which doesn't include a time.DateOnlymatches the database type better.

DateOnlyhas a range from 0001-01-01 through 9999-12-31, just likeDateTime. You can specify a specific calendar in theDateOnlyconstructor. However, aDateOnlyobject always represents a date in the proleptic Gregorian calendar, regardless of which calendar was used to construct it. For example, you can build the date from a Hebrew calendar, but the date is converted to Gregorian:

var hebrewCalendar = new System.Globalization.HebrewCalendar();var theDate = new DateOnly(5776, 2, 8, hebrewCalendar); // 8 Cheshvan 5776Console.WriteLine(theDate);/* This example produces the following output: * * 10/21/2015*/

Dim hebrewCalendar = New System.Globalization.HebrewCalendar()Dim theDate = New DateOnly(5776, 2, 8, hebrewCalendar) ' 8 Cheshvan 5776Console.WriteLine(theDate)' This example produces the following output'' 10/21/2015

DateOnly examples

Use the following examples to learn aboutDateOnly:

• Convert DateTime to DateOnly
• Add or subtract days, months, years
• Parse and format DateOnly
• Compare DateOnly

Convert DateTime to DateOnly

Use theDateOnly.FromDateTimestatic method to create aDateOnlytype from aDateTimetype, as demonstrated in the following code:

var today = DateOnly.FromDateTime(DateTime.Now);Console.WriteLine($"Today is {today}");/* This example produces output similar to the following: * * Today is 12/28/2022*/

Dim today = DateOnly.FromDateTime(DateTime.Now)Console.WriteLine($"Today is {today}")' This example produces output similar to the following' ' Today is 12/28/2022

Add or subtract days, months, years

There are three methods used to adjust aDateOnlystructure:AddDays,AddMonths, andAddYears. Each method takes an integer parameter, and increases the date by that measurement. If a negative number is provided, the date is decreased by that measurement. The methods return a new instance ofDateOnly, as the structure is immutable.

var theDate = new DateOnly(2015, 10, 21);var nextDay = theDate.AddDays(1);var previousDay = theDate.AddDays(-1);var decadeLater = theDate.AddYears(10);var lastMonth = theDate.AddMonths(-1);Console.WriteLine($"Date: {theDate}");Console.WriteLine($" Next day: {nextDay}");Console.WriteLine($" Previous day: {previousDay}");Console.WriteLine($" Decade later: {decadeLater}");Console.WriteLine($" Last month: {lastMonth}");/* This example produces the following output: * * Date: 10/21/2015 * Next day: 10/22/2015 * Previous day: 10/20/2015 * Decade later: 10/21/2025 * Last month: 9/21/2015*/

Dim theDate = New DateOnly(2015, 10, 21)Dim nextDay = theDate.AddDays(1)Dim previousDay = theDate.AddDays(-1)Dim decadeLater = theDate.AddYears(10)Dim lastMonth = theDate.AddMonths(-1)Console.WriteLine($"Date: {theDate}")Console.WriteLine($" Next day: {nextDay}")Console.WriteLine($" Previous day: {previousDay}")Console.WriteLine($" Decade later: {decadeLater}")Console.WriteLine($" Last month: {lastMonth}")' This example produces the following output' ' Date: 10/21/2015' Next day: 10/22/2015' Previous day: 10/20/2015' Decade later: 10/21/2025' Last month: 9/21/2015

Parse and format DateOnly

DateOnlycan be parsed from a string, just like theDateTimestructure. All of the standard .NET date-based parsing tokens work withDateOnly. When converting aDateOnlytype to a string, you can use standard .NET date-based formatting patterns too. For more information about formatting strings, seeStandard date and time format strings.

var theDate = DateOnly.ParseExact("21 Oct 2015", "dd MMM yyyy", CultureInfo.InvariantCulture); // Custom formatvar theDate2 = DateOnly.Parse("October 21, 2015", CultureInfo.InvariantCulture);Console.WriteLine(theDate.ToString("m", CultureInfo.InvariantCulture)); // Month day patternConsole.WriteLine(theDate2.ToString("o", CultureInfo.InvariantCulture)); // ISO 8601 formatConsole.WriteLine(theDate2.ToLongDateString());/* This example produces the following output: * * October 21 * 2015-10-21 * Wednesday, October 21, 2015*/

Dim theDate = DateOnly.ParseExact("21 Oct 2015", "dd MMM yyyy", CultureInfo.InvariantCulture) ' Custom formatDim theDate2 = DateOnly.Parse("October 21, 2015", CultureInfo.InvariantCulture)Console.WriteLine(theDate.ToString("m", CultureInfo.InvariantCulture)) ' Month day patternConsole.WriteLine(theDate2.ToString("o", CultureInfo.InvariantCulture)) ' ISO 8601 formatConsole.WriteLine(theDate2.ToLongDateString())' This example produces the following output' ' October 21' 2015-10-21' Wednesday, October 21, 2015

Compare DateOnly

DateOnlycan be compared with other instances. For example, you can check if a date is before or after another, or if a date today matches a specific date.

var theDate = DateOnly.ParseExact("21 Oct 2015", "dd MMM yyyy", CultureInfo.InvariantCulture); // Custom formatvar theDate2 = DateOnly.Parse("October 21, 2015", CultureInfo.InvariantCulture);var dateLater = theDate.AddMonths(6);var dateBefore = theDate.AddDays(-10);Console.WriteLine($"Consider {theDate}...");Console.WriteLine($" Is '{nameof(theDate2)}' equal? {theDate == theDate2}");Console.WriteLine($" Is {dateLater} after? {dateLater > theDate} ");Console.WriteLine($" Is {dateLater} before? {dateLater < theDate} ");Console.WriteLine($" Is {dateBefore} after? {dateBefore > theDate} ");Console.WriteLine($" Is {dateBefore} before? {dateBefore < theDate} ");/* This example produces the following output: * * Consider 10/21/2015 * Is 'theDate2' equal? True * Is 4/21/2016 after? True * Is 4/21/2016 before? False * Is 10/11/2015 after? False * Is 10/11/2015 before? True*/

Dim theDate = DateOnly.ParseExact("21 Oct 2015", "dd MMM yyyy", CultureInfo.InvariantCulture) ' Custom formatDim theDate2 = DateOnly.Parse("October 21, 2015", CultureInfo.InvariantCulture)Dim dateLater = theDate.AddMonths(6)Dim dateBefore = theDate.AddDays(-10)Console.WriteLine($"Consider {theDate}...")Console.WriteLine($" Is '{NameOf(theDate2)}' equal? {theDate = theDate2}")Console.WriteLine($" Is {dateLater} after? {dateLater > theDate} ")Console.WriteLine($" Is {dateLater} before? {dateLater < theDate} ")Console.WriteLine($" Is {dateBefore} after? {dateBefore > theDate} ")Console.WriteLine($" Is {dateBefore} before? {dateBefore < theDate} ")' This example produces the following output' ' Consider 10/21/2015' Is 'theDate2' equal? True' Is 4/21/2016 after? True' Is 4/21/2016 before? False' Is 10/11/2015 after? False' Is 10/11/2015 before? True

The TimeOnly structure

TheTimeOnlystructure represents a time-of-day value, such as a daily alarm clock or what time you eat lunch each day.TimeOnlyis limited to the range of00:00:00.0000000-23:59:59.9999999, a specific time of day.

Prior to theTimeOnlytype being introduced, programmers typically used either theDateTimetype or theTimeSpantype to represent a specific time. However, using these structures to simulate a time without a date may introduce some problems, whichTimeOnlysolves:

• TimeSpanrepresents elapsed time, such as time measured with a stopwatch. The upper range is more than 29,000 years, and its value can be negative to indicate moving backwards in time. A negativeTimeSpandoesn't indicate a specific time of the day.

• IfTimeSpanis used as a time of day, there's a risk that it could be manipulated to a value outside of the 24-hour day.TimeOnlydoesn't have this risk. For example, if an employee's work shift starts at 18:00 and lasts for 8 hours, adding 8 hours to theTimeOnlystructure rolls over to 2:00

• UsingDateTimefor a time of day requires that an arbitrary date be associated with the time, and then later disregarded. It's common practice to chooseDateTime.MinValue(0001-01-01) as the date, however, if hours are subtracted from theDateTimevalue, anOutOfRangeexception might occur.TimeOnlydoesn't have this problem as the time rolls forwards and backwards around the 24-hour timeframe.

• Serializing aDateTimestructure includes the date component, which may obscure the intent of the data. Also,TimeOnlyserializes less data.

TimeOnly examples

Use the following examples to learn aboutTimeOnly:

• Convert DateTime to TimeOnly
• Add or subtract time
• Parse and format TimeOnly
• Work with TimeSpan and DateTime
• Arithmetic operators and comparing TimeOnly

Convert DateTime to TimeOnly

Use theTimeOnly.FromDateTimestatic method to create aTimeOnlytype from aDateTimetype, as demonstrated in the following code:

var now = TimeOnly.FromDateTime(DateTime.Now);Console.WriteLine($"It is {now} right now");/* This example produces output similar to the following: * * It is 2:01 PM right now*/

Dim now = TimeOnly.FromDateTime(DateTime.Now)Console.WriteLine($"It is {now} right now")' This example produces output similar to the following' ' It is 2:01 PM right now

Add or subtract time

There are three methods used to adjust aTimeOnlystructure:AddHours,AddMinutes, andAdd. BothAddHoursandAddMinutestake an integer parameter, and adjust the value accordingly. You can use a negative value to subtract and a positive value to add. The methods return a new instance ofTimeOnlyis returned, as the structure is immutable. TheAddmethod takes aTimeSpanparameter and adds or subtracts the value from theTimeOnlyvalue.

BecauseTimeOnlyonly represents a 24-hour period, it rolls over forwards or backwards appropriately when adding values supplied to those three methods. For example, if you use a value of01:30:00to represent 1:30 AM, then add -4 hours from that period, it rolls backwards to21:30:00, which is 9:30 PM. There are method overloads forAddHours,AddMinutes, andAddthat capture the number of days rolled over.

var theTime = new TimeOnly(7, 23, 11);var hourLater = theTime.AddHours(1);var minutesBefore = theTime.AddMinutes(-12);var secondsAfter = theTime.Add(TimeSpan.FromSeconds(10));var daysLater = theTime.Add(new TimeSpan(hours: 21, minutes: 200, seconds: 83), out int wrappedDays);var daysBehind = theTime.AddHours(-222, out int wrappedDaysFromHours);Console.WriteLine($"Time: {theTime}");Console.WriteLine($" Hours later: {hourLater}");Console.WriteLine($" Minutes before: {minutesBefore}");Console.WriteLine($" Seconds after: {secondsAfter}");Console.WriteLine($" {daysLater} is the time, which is {wrappedDays} days later");Console.WriteLine($" {daysBehind} is the time, which is {wrappedDaysFromHours} days prior");/* This example produces the following output: * * Time: 7:23 AM * Hours later: 8:23 AM * Minutes before: 7:11 AM * Seconds after: 7:23 AM * 7:44 AM is the time, which is 1 days later * 1:23 AM is the time, which is -9 days prior*/

Dim wrappedDays As IntegerDim wrappedDaysFromHours As IntegerDim theTime = New TimeOnly(7, 23, 11)Dim hourLater = theTime.AddHours(1)Dim minutesBefore = theTime.AddMinutes(-12)Dim secondsAfter = theTime.Add(TimeSpan.FromSeconds(10))Dim daysLater = theTime.Add(New TimeSpan(hours:=21, minutes:=200, seconds:=83), wrappedDays)Dim daysBehind = theTime.AddHours(-222, wrappedDaysFromHours)Console.WriteLine($"Time: {theTime}")Console.WriteLine($" Hours later: {hourLater}")Console.WriteLine($" Minutes before: {minutesBefore}")Console.WriteLine($" Seconds after: {secondsAfter}")Console.WriteLine($" {daysLater} is the time, which is {wrappedDays} days later")Console.WriteLine($" {daysBehind} is the time, which is {wrappedDaysFromHours} days prior")' This example produces the following output' ' Time: 7:23 AM' Hours later: 8:23 AM' Minutes before: 7:11 AM' Seconds after: 7:23 AM' 7:44 AM is the time, which is 1 days later ' 1:23 AM is the time, which is -9 days prior

Parse and format TimeOnly

TimeOnlycan be parsed from a string, just like theDateTimestructure. All of the standard .NET time-based parsing tokens work withTimeOnly. When converting aTimeOnlytype to a string, you can use standard .NET date-based formatting patterns too. For more information about formatting strings, seeStandard date and time format strings.

var theTime = TimeOnly.ParseExact("5:00 pm", "h:mm tt", CultureInfo.InvariantCulture); // Custom formatvar theTime2 = TimeOnly.Parse("17:30:25", CultureInfo.InvariantCulture);Console.WriteLine(theTime.ToString("o", CultureInfo.InvariantCulture)); // Round-trip pattern.Console.WriteLine(theTime2.ToString("t", CultureInfo.InvariantCulture)); // Long time formatConsole.WriteLine(theTime2.ToLongTimeString());/* This example produces the following output: * * 17:00:00.0000000 * 17:30 * 5:30:25 PM*/

Dim theTime = TimeOnly.ParseExact("5:00 pm", "h:mm tt", CultureInfo.InvariantCulture) ' Custom formatDim theTime2 = TimeOnly.Parse("17:30:25", CultureInfo.InvariantCulture)Console.WriteLine(theTime.ToString("o", CultureInfo.InvariantCulture)) ' Round-trip pattern.Console.WriteLine(theTime2.ToString("t", CultureInfo.InvariantCulture)) ' Long time formatConsole.WriteLine(theTime2.ToLongTimeString())' This example produces the following output' ' 17:00:00.0000000' 17:30' 5:30:25 PM

Serialize DateOnly and TimeOnly types

With .NET 7+,System.Text.Jsonsupports serializing and deserializingDateOnlyandTimeOnlytypes. Consider the following object:

sealed file record Appointment( Guid Id, string Description, DateOnly Date, TimeOnly StartTime, TimeOnly EndTime);

Public NotInheritable Class Appointment Public Property Id As Guid Public Property Description As String Public Property DateValue As DateOnly? Public Property StartTime As TimeOnly? Public Property EndTime As TimeOnly?End Class

The following example serializes anAppointmentobject, displays the resulting JSON, and then deserializes it back into a new instance of theAppointmenttype. Finally, the original and newly deserialized instances are compared for equality and the results are written to the console:

Appointment originalAppointment = new( Id: Guid.NewGuid(), Description: "Take dog to veterinarian.", Date: new DateOnly(2002, 1, 13), StartTime: new TimeOnly(5,15), EndTime: new TimeOnly(5, 45));string serialized = JsonSerializer.Serialize(originalAppointment);Console.WriteLine($"Resulting JSON: {serialized}");Appointment deserializedAppointment = JsonSerializer.Deserialize(serialized)!;bool valuesAreTheSame = originalAppointment == deserializedAppointment;Console.WriteLine($""" Original record has the same values as the deserialized record: {valuesAreTheSame} """);

Dim originalAppointment As New Appointment With { .Id = Guid.NewGuid(), .Description = "Take dog to veterinarian.", .DateValue = New DateOnly(2002, 1, 13), .StartTime = New TimeOnly(5, 3, 1), .EndTime = New TimeOnly(5, 3, 1)} Dim serialized As String = JsonSerializer.Serialize(originalAppointment) Console.WriteLine($"Resulting JSON: {serialized}") Dim deserializedAppointment As Appointment = JsonSerializer.Deserialize(Of Appointment)(serialized) Dim valuesAreTheSame As Boolean = (originalAppointment.DateValue = deserializedAppointment.DateValue AndAlso originalAppointment.StartTime = deserializedAppointment.StartTime AndAlso originalAppointment.EndTime = deserializedAppointment.EndTime AndAlso originalAppointment.Id = deserializedAppointment.Id AndAlso originalAppointment.Description = deserializedAppointment.Description) Console.WriteLine( $"Original object has the same values as the deserialized object: {valuesAreTheSame}")

In the preceding code:

• AnAppointmentobject is instantiated and assigned to theappointmentvariable.
• Theappointmentinstance is serialized to JSON usingJsonSerializer.Serialize.
• The resulting JSON is written to the console.
• The JSON is deserialized back into a new instance of theAppointmenttype usingJsonSerializer.Deserialize.
• The original and newly deserialized instances are compared for equality.
• The result of the comparison is written to the console.

For more information, seeHow to serialize and deserialize (marshal and unmarshal) JSON in .NET.

Work with TimeSpan and DateTime

TimeOnlycan be created from and converted to aTimeSpan. Also,TimeOnlycan be used with aDateTime, either to create theTimeOnlyinstance, or to create aDateTimeinstance as long as a date is provided.

The following example creates aTimeOnlyobject from aTimeSpan, and then converts it back:

// TimeSpan must in the range of 00:00:00.0000000 to 23:59:59.9999999var theTime = TimeOnly.FromTimeSpan(new TimeSpan(23, 59, 59));var theTimeSpan = theTime.ToTimeSpan();Console.WriteLine($"Variable '{nameof(theTime)}' is {theTime}");Console.WriteLine($"Variable '{nameof(theTimeSpan)}' is {theTimeSpan}");/* This example produces the following output: * * Variable 'theTime' is 11:59 PM * Variable 'theTimeSpan' is 23:59:59*/

' TimeSpan must in the range of 00:00:00.0000000 to 23:59:59.9999999Dim theTime = TimeOnly.FromTimeSpan(New TimeSpan(23, 59, 59))Dim theTimeSpan = theTime.ToTimeSpan()Console.WriteLine($"Variable '{NameOf(theTime)}' is {theTime}")Console.WriteLine($"Variable '{NameOf(theTimeSpan)}' is {theTimeSpan}")' This example produces the following output' ' Variable 'theTime' is 11:59 PM' Variable 'theTimeSpan' is 23:59:59

The following example creates aDateTimefrom aTimeOnlyobject, with an arbitrary date chosen:

var theTime = new TimeOnly(11, 25, 46); // 11:25 PM and 46 secondsvar theDate = new DateOnly(2015, 10, 21); // October 21, 2015var theDateTime = theDate.ToDateTime(theTime);var reverseTime = TimeOnly.FromDateTime(theDateTime);Console.WriteLine($"Date only is {theDate}");Console.WriteLine($"Time only is {theTime}");Console.WriteLine();Console.WriteLine($"Combined to a DateTime type, the value is {theDateTime}");Console.WriteLine($"Converted back from DateTime, the time is {reverseTime}");/* This example produces the following output: * * Date only is 10/21/2015 * Time only is 11:25 AM * * Combined to a DateTime type, the value is 10/21/2015 11:25:46 AM * Converted back from DateTime, the time is 11:25 AM*/

Dim theTime = New TimeOnly(11, 25, 46) ' 11: 25 PM And 46 secondsDim theDate = New DateOnly(2015, 10, 21) ' October 21, 2015Dim theDateTime = theDate.ToDateTime(theTime)Dim reverseTime = TimeOnly.FromDateTime(theDateTime)Console.WriteLine($"Date only is {theDate}")Console.WriteLine($"Time only is {theTime}")Console.WriteLine()Console.WriteLine($"Combined to a DateTime type, the value is {theDateTime}")Console.WriteLine($"Converted back from DateTime, the time is {reverseTime}")' This example produces the following output' ' Date only is 10/21/2015' Time only is 11:25 AM' ' Combined to a DateTime type, the value is 10/21/2015 11:25:46 AM' Converted back from DateTime, the time is 11:25 AM

Arithmetic operators and comparing TimeOnly

TwoTimeOnlyinstances can be compared with one another, and you can use theIsBetweenmethod to check if a time is between two other times. When an addition or subtraction operator is used on aTimeOnly, aTimeSpanis returned, representing a duration of time.

var start = new TimeOnly(10, 12, 01); // 10:12:01 AMvar end = new TimeOnly(14, 00, 53); // 02:00:53 PMvar outside = start.AddMinutes(-3);var inside = start.AddMinutes(120);Console.WriteLine($"Time starts at {start} and ends at {end}");Console.WriteLine($" Is {outside} between the start and end? {outside.IsBetween(start, end)}");Console.WriteLine($" Is {inside} between the start and end? {inside.IsBetween(start, end)}");Console.WriteLine($" Is {start} less than {end}? {start < end}");Console.WriteLine($" Is {start} greater than {end}? {start > end}");Console.WriteLine($" Does {start} equal {end}? {start == end}");Console.WriteLine($" The time between {start} and {end} is {end - start}");/* This example produces the following output: * * Time starts at 10:12 AM and ends at 2:00 PM * Is 10:09 AM between the start and end? False * Is 12:12 PM between the start and end? True * Is 10:12 AM less than 2:00 PM? True * Is 10:12 AM greater than 2:00 PM? False * Does 10:12 AM equal 2:00 PM? False * The time between 10:12 AM and 2:00 PM is 03:48:52*/

Dim startDate = New TimeOnly(10, 12, 1) ' 10:12:01 AMDim endDate = New TimeOnly(14, 0, 53) ' 02:00:53 PMDim outside = startDate.AddMinutes(-3)Dim inside = startDate.AddMinutes(120)Console.WriteLine($"Time starts at {startDate} and ends at {endDate}")Console.WriteLine($" Is {outside} between the start and end? {outside.IsBetween(startDate, endDate)}")Console.WriteLine($" Is {inside} between the start and end? {inside.IsBetween(startDate, endDate)}")Console.WriteLine($" Is {startDate} less than {endDate}? {startDate < endDate}")Console.WriteLine($" Is {startDate} greater than {endDate}? {startDate > endDate}")Console.WriteLine($" Does {startDate} equal {endDate}? {startDate = endDate}")Console.WriteLine($" The time between {startDate} and {endDate} is {endDate - startDate}")' This example produces the following output' ' Time starts at 10:12 AM And ends at 2:00 PM' Is 10:09 AM between the start And end? False' Is 12:12 PM between the start And end? True' Is 10:12 AM less than 2:00 PM? True' Is 10:12 AM greater than 2:00 PM? False' Does 10:12 AM equal 2:00 PM? False' The time between 10:12 AM and 2:00 PM is 03:48:52