How to get a Timespan of 1 year?

Question

I want to get a Timespan structure which represent a year in C#.

Twentyfour

TimeSpan is a structure, not an object :-) – Tedman

Leap year, Normal year or Average year? – Bandicoot

This question leads to a good discussion +1 – Hypoglycemia

@Hans Kesting Structures inherit from System.ValueType, which in turn inherits from System.Object :P – Mairamaire

A timespan cannot represent the concept of a year, since a year doesn't have a constant length. – Schroeder

According to google, the average year has 365.2422 days; You can approximate the average year in a TimeSpan as follows:TimeSpan.FromDays(365.2422D) (and it's actually decently accurate for long term calculations; I was surprised). – Cham

Answer 1

The tricky thing is that what a year is, depends on where it starts.

You can do

DateTime now = DateTime.Now;
TimeSpan span = now.AddYears(1) - now;

This would give you the 1 year timespan from the current moment to one year later

Playgoer

sehe is correct a timespan of a year will be unique to every start point. – Varney

great, thanks, but could you add some examples of how it behaves? why it is important that 1year timespan depends on where it starts? right now I cant imagine where could be the problem, but I know it has to be somewhere :) thanks – Categorical

oh now i realized, why when i add 1 year like in this answer and then get the XmlConvert.ToString(span) it always makes days from the year... I want an output like PnYnMnDnHnMnS... and it always makes PnDnH... the years and months are not present why? – Categorical

Answer 2

The key question here is: which year?

The length of the timespan obviously depends on whether the year you want is a leap year or not and when it starts.

If you want one year starting from today go with @sehe's answer.

If you want the current year go with @Oyvind,

If you want a reasonable approximation you can go with @Nayan, or for a 365.25 approximation use:

TimeSpan oneYearSpan = new TimeSpan(365, 6, 0, 0);

Aeolipile

Answer 3

You can't, as a year doesn't have a fixed length (is it 365 or 366 days or about 365.25?). That's also why you can't have a month as TimeSpan (28, 29, 30, 31 days??)

Patriciapatrician

and forgetting about leap seconds and other anomalies for a ... second ... there – Playgoer

@BoltClock: yeah Hans used one of his spare seconds to ninja edit that right in :) – Playgoer

@sehe: so that's what you call a quick edit without it showing up as one, cool! – Carson

According to google, TimeSpan.FromDays(30.42D), and TimeSpan.FromDays(365.2422D) would be the respective averages. -- For years it's surprisingly accurate (months is less accurate). – Cham

Answer 4

DateTime intialDate = Date.Now.Date;
TimeSpan yearSpan = intialDate.AddYears(1).Subtract(intialDate)

As other peoplehave mentioned you may want to consider leap years. In that case you can intiate intialDate accordingly.

Stinkstone

Answer 5

Rough example:

TimeSpan oneYearSpan = new TimeSpan(365, 0, 0, 0);

Will this do?

Blew

Answer 6

If you want to be pretty accurate you could use the number of nano seconds in a year. I think that this moves by 0.5 seconds every century, so should be good for a long while yet!

public TimeSpan MyYear
{
    get
    { 
        // Year = 3.1556926 × 10^16 nanoseconds
        return new TimeSpan(31556926000000000);
    }
}

There are already some good answers on this page, this is just another option.

Hypoglycemia

And in a leap year, you're a full day off from what moest people would expect. Not a god idea. – Lapham

Answer 7

It depends on which year you want to represent, since not all years are of equal length.

This is the way to find the length of 2010 for example:

var timestamp = new DateTime(2011, 1, 1) - new DateTime(2010, 1, 1);

Change the year in the DateTimes to find the length of the year you want.

Helfant

Answer 8

Here's how to do this, utilizing the IsLeapYear to determain number of day.

int span = DateTime.IsLeapYear(1996) ? 366: 365;
var year1996 = new TimeSpan(span, 0, 0, 0);

Wanting

Not every timespan that lasts on eyear starts on January 1st. Do not do it like this. – Lapham