TimeSpan to DateTime conversion

Question

I want to convert a Timespan to Datetime. How can I do this?

I found one method on Google:

DateTime dt;
TimeSpan ts="XXX";

//We can covnert 'ts' to 'dt' like this:

dt= Convert.ToDateTime(ts.ToString());

Is there any other way to do this?

Answer 1

It is not very logical to convert TimeSpan to DateTime. Try to understand what leppie said above. TimeSpan is a duration say 6 Days 5 Hours 40 minutes. It is not a Date. If I say 6 Days; Can you deduce a Date from it? The answer is NO unless you have a REFERENCE Date.

So if you want to convert TimeSpan to DateTime you need a reference date. 6 Days & 5 Hours from when? So you can write something like this:

 DateTime dt = new DateTime(2012, 01, 01);
 TimeSpan ts = new TimeSpan(1, 0, 0, 0, 0);
 dt = dt + ts;

Answer 2

While the selected answer is strictly correct, I believe I understand what the OP is trying to get at here as I had a similar issue.

I had a TimeSpan which I wished to display in a grid control (as just hh:mm) but the grid didn't appear to understand TimeSpan, only DateTime . The OP has a similar scenario where only the TimeSpan is the relevant part but didn't consider the necessity of adding the DateTime reference point.

So, as indicated above, I simply added DateTime.MinValue (though any date will do) which is subsequently ignored by the grid when it renders the timespan as a time portion of the resulting date.

Answer 3

TimeSpan can be added to a fresh DateTime to achieve this.

TimeSpan ts="XXX";
DateTime dt = new DateTime() + ts;

But as mentioned before, it is not strictly logical without a valid start date. I have encountered a use-case where i required only the time aspect. will work fine as long as the logic is correct.

Answer 4

You need a reference date for this to be useful.

An example from http://msdn.microsoft.com/en-us/library/system.datetime.add.aspx

// Calculate what day of the week is 36 days from this instant.  
System.DateTime today = System.DateTime.Now;  
System.TimeSpan duration = new System.TimeSpan(36, 0, 0, 0);  
System.DateTime answer = today.Add(duration);  
System.Console.WriteLine("{0:dddd}", answer);  

Answer 5

var StartTime = new DateTime(item.StartTime.Ticks);

Answer 6

If you only need to show time value in a datagrid or label similar, best way is convert directly time in datetime datatype.

SELECT CONVERT(datetime,myTimeField) as myTimeField FROM Table1

Answer 7

You could also use DateTime.FromFileTime(finishTime) where finishTme is a long containing the ticks of a time. Or FromFileTimeUtc.

Answer 8

An easy method, use ticks:

new DateTime((DateTime.Now - DateTime.Now.AddHours(-1.55)).Ticks).ToString("HH:mm:ss:fff")

This function will give you a date (Without Day / Month / Year)

Answer 9

A problem with all of the above is that the conversion returns the incorrect number of days as specified in the TimeSpan.
Using the above, the below returns 3 and not 2.

Ideas on how to preserve the 2 days in the TimeSpan arguments and return them as the DateTime day?

public void should_return_totaldays()
{
    _ts = new TimeSpan(2, 1, 30, 10);
    var format = "dd";
    var returnedVal = _ts.ToString(format);
    Assert.That(returnedVal, Is.EqualTo("2")); //returns 3 not 2
}

Answer 10

First, convert the timespan to a string, then to DateTime, then back to a string:

Convert.ToDateTime(timespan.SelectedTime.ToString()).ToShortTimeString();