How do I represent a time only value in .NET?

Question

Is there a way one can represent a time only value in .NET without the date? For example, indicating the opening time of a shop?

TimeSpan indicates a range, whereas I only want to store a time value. Using DateTime to indicate this would result in new DateTime(1,1,1,8,30,0) which is not really desirable.

Solution 1

As others have said, you can use a DateTime and ignore the date, or use a TimeSpan. Personally I'm not keen on either of these solutions, as neither type really reflects the concept you're trying to represent - I regard the date/time types in .NET as somewhat on the sparse side which is one of the reasons I started Noda Time. In Noda Time, you can use the LocalTime type to represent a time of day.

Note that as of .NET 6, there are TimeOnly and DateOnly types which are roughly equivalent to Noda Time's LocalTime and LocalDate types.

One thing to consider: the time of day is not necessarily the length of time since midnight on the same day...

(As another aside, if you're also wanting to represent a closing time of a shop, you may find that you want to represent 24:00, i.e. the time at the end of the day. Most date/time APIs - including Noda Time - don't allow that to be represented as a time-of-day value.)

Solution 2

You can use timespan

TimeSpan timeSpan = new TimeSpan(2, 14, 18);
Console.WriteLine(timeSpan.ToString());     // Displays "02:14:18".

[Edit]
Considering the other answers and the edit to the question, I would still use TimeSpan. No point in creating a new structure where an existing one from the framework suffice.
On these lines you would end up duplicating many native data types.

Solution 3

If that empty Date really bugs you, you can also to create a simpler Time structure:

// more work is required to make this even close to production ready
class Time
{
    // TODO: don't forget to add validation
    public int Hours   { get; set; }
    public int Minutes { get; set; }
    public int Seconds { get; set; }

    public override string ToString()
    {  
        return String.Format(
            "{0:00}:{1:00}:{2:00}",
            this.Hours, this.Minutes, this.Seconds);
    }
}

Or, why to bother: if you don't need to do any calculation with that information, just store it as String.

Solution 4

I say use a DateTime. If you don't need the date portion, just ignore it. If you need to display just the time to the user, output it formatted to the user like this:

DateTime.Now.ToString("t");  // outputs 10:00 PM

It seems like all the extra work of making a new class or even using a TimeSpan is unnecessary.

Solution 5

I think Rubens' class is a good idea so thought to make an immutable sample of his Time class with basic validation.

class Time
{
    public int Hours   { get; private set; }
    public int Minutes { get; private set; }
    public int Seconds { get; private set; }

    public Time(uint h, uint m, uint s)
    {
        if(h > 23 || m > 59 || s > 59)
        {
            throw new ArgumentException("Invalid time specified");
        }
        Hours = (int)h; Minutes = (int)m; Seconds = (int)s;
    }

    public Time(DateTime dt)
    {
        Hours = dt.Hour;
        Minutes = dt.Minute;
        Seconds = dt.Second;
    }

    public override string ToString()
    {  
        return String.Format(
            "{0:00}:{1:00}:{2:00}",
            this.Hours, this.Minutes, this.Seconds);
    }
}

View more solutions

Comments

[Marcel Jackwerth]

Exactly. DateTime uses TimeSpan for exactly that purpose. Doc for DateTime.TimeSpan Property: "A TimeSpan that represents the fraction of the day that has elapsed since midnight."

[sduplooy]

TimeSpan indicates an interval whereas the time I'm talking about is not an interval, but a single fixed point over a range of dates.

[John G]

It may be used as a fixed point at well, and as you specified in the question, it is without date. After all you decide how to use these datatypes to your benifit.

[Kris Krause]

Hmmm... maybe... but why reinvent the wheel? If the language already has a class/structure (which C# and VB.NET do), then go with it. But I do understand where you are trying to go with your answer.

[John G]

How would this structure be any different from TimeSpan, this would just duplicate it in a way.

[Noon Silk]

Downvoting you due to the existance of TimeSpan, which already handles this, and in a significantly better way.

[Rubens Farias]

@silky, I wrote this after reading first answer; OP said on question he doesn't wanted to use TimeSpan; I, personally, would opt to use a plain DateTime

[Jon Skeet]

@John G: While it can be used to represent a fixed point, I agree with the OP - overloading the use of TimeSpan like this is somewhat ugly. It's the best that's available within the framework itself, but that's not the same as saying it's pleasant.

[jason]

"[T]he time of day is not necessarily the length of time since midnight on the same day..." Is daylight savings time the only reason? Just curious why you left it indefinite.

[Jon Skeet]

@MarcelJ: I take issue with that description of DateTime.Time. At 3am on March 28th in London, there will only have been 2 hours since midnight, for example. "Time of day" != "elapsed time since midnight." I realise that's MSDN's description rather than yours, but I'm just pointing out the problems with it.

[Jon Skeet]

@Jason: Daylight saving is the only reason I can think of offhand - ignoring leap seconds as irrelevant to most applications. I mostly left it that way to encourage others to think why that might be. I reckon it's a good thing for people to think a bit more deeply about dates/times than they currently do :)

[sduplooy]

LocalTime is exactly what I need to support my requirement.

[Jon Skeet]

@sduplooy: Fancy helping us port it from Joda Time then? :)

[sduplooy]

Sure, I think I'll start on LocalTime :)

[John G]

You can treat the timepsan in such a scenario to be a GMT representation, again an effecive usage as required.

[Noon Silk]

Rubens: Fair enough; I'll remove the downvote via a useless edit.

[Jon Skeet]

@John G: Yes, you can do that. I just think it's pretty ugly.

[John G]

Still IMHO is better than a new set of classes to duplicate natively available data structure.

[SND]

the time of day is not necessarily the length of time since midnight on the same day: also true if I travel and change timezones.

[Jon Skeet]

@AndyM: I don't think "you changing time zone" is relevant here. DST changes are relevant, but a simple time of day doesn't need to take into account one person changing time zone.

[Zaid Masud]

@KrisKrause I don't think this is reinventing the wheel, TimeSpan gives you much more than just a Time. If using it as just a Time, it can be misinterpreted and misused e.g. a property like Days has no meaning.

[Zaid Masud]

+1 This is better than a TimeSpan because it has less possibilities of misinterpretation... a TimeSpan is really meant to be used as an interval (see MSDN) so a property like Days has no meaning when TimeSpan is used as a Time

[Giri Aakula]

@JonSkeet I want to keep track of time in a song, or a video. Another way of thinking: You are playing a video, and on given point in time I want to show some information, so my time has to be tied to the video time and not the time of the day and obviously with no date, since that video could be played at any day at any time, anywhere. Does Noda takes care of that, or do you have any other ideas?

[Jon Skeet]

@Oakcool: Yes, you want an elapsed time - a Duration in Noda Time, and a TimeSpan in .NET.

[Giri Aakula]

Not sure I understand. Here is what I need: An array of time {00:01:30, 00:06:30, 01:30:30}, so I can while watching a video say, at [0], "oakcool enters the scene and looks very confused,[see his profile here", at [1], Jon Skeet enters the scene and explains it all [see his profile here], at [2], both walk away to find some beer [see solution here]. But with DateTime that is not good enough.

[Jon Skeet]

@Oakcool: Exactly as I said on May 18th: Duration in Noda Time, or TimeSpan in the BCL. I'd probably encapsulate the "place in video + comment" as a type, and then have an array of that type.

[Chris Marisic]

Given new DateTime().TimeSpan and that new TimeSpan(hour, minute, second) both exists I find it pretty compelling that they fully intended TimeSpan to be used to start clock time and not just time deltas.

[Pharap]

As of .Net 3.5, MSDN documents that "The TimeSpan structure can also be used to represent the time of day, but only if the time is unrelated to a particular date.". In other words, this is exactly the solution to the proposed question.

[Jon Skeet]

@Pharap: Just because it can be used that way doesn't make that a good idea. It means that TimeSpan is used for two very different purposes - just like DateTime is used for values in UTC, local and unspecified time zones. Fundamentally, the date/time types in the framework have significant conceptual issues, IMO.

[Pharap]

@JonSkeet I don't disagree that .Net's time-related features are lacking (particularly in comparison to Java and its time unit conversions) but I suspect they're more concerned with their shiny new features than fixing the things they screwed up. It might seem dirty to be using DateTime and TimeSpan for things that seem to go against their name, but it depends how you view them. Personally I think it makes sense to think that a time of day is not a fixed point on its own. Without a date as a reference point, a time of day is just an offset into some arbitrary day.

[Jon Skeet]

@Pharap: I think you've missed my point - I'm basically saying that it's a bad fit, and there are better options available; not within the core framework, but in Noda Time and undoubtedly other libraries. In particular, there are things you can legitimately do with TimeSpan (such as adding two values) which simply don't make sense for time-of-day values. That sort of thing is why I think it's a bad idea to use TimeSpan to represent a time of day.

[Pharap]

@JonSkeet It's not less than what people do with Vectors in most physics and game libraries. Instead of declaring Points and Vectors to be separate, Vectors are used for both. Besides, sometimes a solution outside the core framework isn't ideal. Say for example if you are developing a library for external consumption, the more dependencies you use, the more dependencies you force on the consumers of your library.

[Jon Skeet]

@Pharap: Whereas I'd say that it's better to use Point and Vector separately, and using a Vector when you mean a Point leads to confusing code. While I agree that adding dependencies isn't a great idea, I do think it's reasonable to point out that TimeSpan really isn't a brilliant fit for "time of day", and that your suggestion that it "this is exactly the solution to the proposed question" is ignoring that. Just because MS does it doesn't make it a good idea :)

[Jon Skeet]

While I think it's reasonable to have a different type, I don't think this is a good solution: 1) it's a mutable value type; 2) it performs no validation of any kind.

[Mona Jalal]

How would you show seconds and mili-seconds in this method?

[Rubens Farias]

@JonSkeet, this old answer was supposed to describe the idea, not to implement the whole concept.

[Jon Skeet]

@Rubens: If you're going to provide any implementation, I think it would be better to avoid obvious bad ideas (mutable value types) and indicate that more work is required to make this even close to production ready.

[Pharap]

@JonSkeet To be honest I think we are just going round in circles. I agree that Point and Vector should be treated seperately and equally, my point was that many well known libraries choose to ignore this for simplicity. Feel free to disagree with MSDN but I'm going to stick with them this time. The OP and anyone else is free to choose whatever suits their situation, whether that is the standard library or an external library, but I know which side I'm sticking with. I can't really say much more without more information about the OP's situation.

[Pharap]

I'm upvoting for the concept of the solution, I'm not 100% happy with your implementation of it, but that's just a personal difference.

[Pharap]

@MonaJalal Milliseconds: DateTime.Now.ToString("hh:mm:ss.fff"); Microseconds: DateTime.Now.ToString("hh:mm:ss.ffffff"); Nanoseconds (if DateTime even has that much resolution): DateTime.Now.ToString("hh:mm:ss.fffffffff"); As per MSDN

[Jon Skeet]

@Pharap: I think we'll have to agree to disagree. I hate it when my code becomes unclear due to using types to represent values they weren't really designed for.

[Chibueze Opata]

Your add methods for minutes and seconds are wrong as they don't account for values above 59.

[Jules]

@Chibueze Opate: you're completely right. This was just quick and dirty. I should put some more work in this code. I will update it later... Thanks for your hint!

[William T. Mallard]

Fun fact: Generating an ADO.net data model using MySQL and Schema First will select TimeSpan as the model data type for any columns with type "Time". It still floors me how relatively unsolved the the whole time problem is. I think it should probably be a separate and required class for any CS degree.

[Daniel James Bryars]

-1, "No point in creating a new structure where an existing one from the framework suffice" - there is a point, not conflating the concept that similar (even identical) implementations as meaning they are the same thing. I accept your answer in this case is pragmatic, I object to the general advice given.

[Daniel James Bryars]

Thinking about "On these lines you would end up duplicating many native data types" you're right. I think it would be nice to be able to "typedef" value types in C# to avoid naked types.

[Timothy Gonzalez]

You would get conflicts this way. How would you then differentiate the time represented with the same values in different time zones (which if we are talking about when a shop opens can't be avoided). For example the times below are all sequential and you have 1am and 2am repeated. 1am UTC-4 = 5am UTC, 2am UTC-4 = 6am UTC, 1am UTC-5 = 7am UTC, 2am UTC-5 = 8am UTC. You can do this, but you just have to think of time span as a duration not a time on a clock in any sense whatsoever which you would look at to see when you can enter the shop.

[Bacon Bits]

Eh. System.Data.SqlDbType.Time maps to System.TimeSpan. That's good enough for me.

[MarioDS]

So, the 5 to 10 minutes it takes to implement a proper type for this seems more work to you than having to consider in the whole codebase, for any future development, that a DateTime property might contain a time only, and has to be formatted like that in those scenarios, and the date portion might need to be ignored? Have fun debugging the occurrences where you will find "0001-01-01 10:00" in your database, in external communications, etc....

[Mafii]

There isi a TimeOfDay property on the .NET DateTime object, so it's supposed to be used for that

[Jon Skeet]

@Mafii: I'd argue that TimeOfDay is a TimeSpan simply because there isn't a more suitable type in .NET. That doesn't mean it's a good use for it. What does a TimeSpan of 5 hours mean? It doesn't necessarily mean that 5 hours have passed since midnight - it means it's 5am. It's a broken representation, IMO.

[Mafii]

@JonSkeet fair enough, sound reasoning. Noda time is great btw.

[shelbypereira]

The validation you have added is extremely important. The main drawback of the TimeSpan class in modelling a time is that the time of day can be more than 24 hours.

[shelbypereira]

Why are the Hours, minutes and seconds using int and not uint? If there is no reason I think they can directly use uint and this avoids the casting in the constructor.

[brighty]

To use Timespan for defining a Time and not a timerange is of course possible, but hour must not be higher than 23, minute not higher than 59 and seonds not higher than 59. Timespan can even accept negative numbers.

[Digital Coyote]

TimeOnly is a framework specific feature. The type could be used in C# 9 if the project targets net6.0 or greater

[Guillaume Raymond]

@DigitalCoyote as far as I understand C#10 is supported by .Net 6

[Digital Coyote]

@GuillaumeRaymond that is correct, but TimeOnly is supported by .Net 6 even if you use C# 9 as your language version. You might use C# 9 or lower to enforce compatability in files linked to projects targeting older frameworks or to allow compiler directives to build an application for an older framework.

[TylerH]

Thanks for updating to include TimeOnly, but I think it should be a bit more prominent than an afterthought (fully grant that you may be intending to do that in a follow-up edit, though)...

[Jon Skeet]

@TylerH: I've moved it to the second paragraph, but frankly if a reader isn't willing to read 4 paragraphs (hardly War and Peace) then I don't have a huge amount of sympathy.

[TylerH]

@JonSkeet Fair point, though I think it's also fair to consider there's a lot of scrolling to do here to get to through all the answers, and when seeing the first paragraph of your answer start as "use TimeSpan", it should be understandable that a reader might not think "Oh, maybe they talk about TimeOnly later on in this answer" :-)

[Jon Skeet]

@TylerH: If someone can't even be bothered to read to the second sentence which discourages the use of TimeSpan, I have even less sympathy. (Even the first sentence says you can (with emphasis) rather than saying "use TimeSpan" - I think you've mischaracterized it significantly.) No-one should use Stack Overflow for "I only need to glance at an answer and half-read the first sentence without actually bothering to think."

[TylerH]

@JonSkeet My point is about readers who've already happened upon the first solutions you offer but are looking for something else/better. If I know there's something called TimeOnly and land on this page looking for an answer that talks about how to use it, for example, I'm not going to bother reading past the first sentence or two of an answer before moving onto the next... because TimeOnly is now the best way to do it, so answers containing it should start with that (albeit with a warning that it's in .NET 6.0 only). And I know SO well. Imagine how a new/anonymous user would behave.

[TylerH]

@JonSkeet I'm not saying that your answer was bad, or that your addition of TimeOnly was not a net positive. I think moving it to the 2nd paragraph is a massive improvement and given that it's only for .NET 6.0 I think that's perfectly fine prominence for now. I was only saying that (in my humble opinion) adding it as an apparent afterthought (below two other options followed by your own custom library, of all things), was not ideal placement.

[Jon Skeet]

@TylerH: I think we'll have to agree to disagree - in particular I don't believe that TimeOnly is the best way to do it, as I'd still recommend using Noda Time - chances are that if you need "time of day" you need other date/time-related concepts as well, and I still believe that Noda Time provides the best way of doing that. I suggest that this comment thread has really gone on long enough at this point though.