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Parse date with time zone, skip timezone

I try to parse date from string which contains time zone information. Input string is 2014-12-17T08:05:39+00:00.
I use DateTime.Parse() method which return me 2014-12-17 09:05:39 (one hour was added). I live in UTC+1:00 (Warsaw), so .NET adopt this date to my local time.
My question is how to use the parse method while skipping time zone, for example for 2014-12-17T08:05:39+00:00 I want to get 2014-12-17 08:05:39.

I would recommend parsing it as a DateTimeOffset instead of as a DateTime. You can then get the DateTime out of that, but it separates the "parsing the data you've been given" step from the "only using the bits I want from that" step.
It's possible that there are ways to make DateTime.Parse behave the way you want using DateTimeStyles - and I'm surprised it's converting to a "local" kind automatically anyway - but using DateTimeOffset will make it clearer.
(Of course I'd really recommend using Noda Time instead, parsing to an OffsetDateTime and then getting the LocalDateTime out of that, but that's a different matter...)

If you remove the part specifying time zone in input string then it parses directly without adjusting to local time. The date.Kind is then Unspecified.
var input = "2014-12-17T08:05:39";
var date = DateTime.Parse(fixedInput);
Although this works you might want to have a look on NodaTime as well.

You should try using DateTimeOffset instead of the DateTime
DateTimeOffset result = DateTimeOffset.Parse("2014-12-17T08:05:39+00:00", CultureInfo.InvariantCulture);
it gives you : 12/17/2014 8:05:39 AM +00:00

Storing current time without milliseconds component

I have a timespan object that needs to hold only time, without date. I would use
DateTime.Now.TimeOfDay
but the problem is it gives time in the format
15:51:51.7368329
I don't want the milliseconds component. How can I trim it out?

You can either use DateTime.Now.Hour/Minute/Second properties or you could use DateTime.Now.ToString("HH:mm:ss").
Refer here for more info: http://msdn.microsoft.com/en-us/library/zdtaw1bw.aspx

I believe this is what you may be after:
TimeSpan timeNow = DateTime.Now.TimeOfDay;
TimeSpan trimmedTimeNow = new TimeSpan(timeNow.Hours, timeNow.Minutes, timeNow.Seconds);

Simply subtract away the millisecond part:
DateTime myTime = DateTime.Now.TimeOfDay;
myTime = myTime.AddMilliseconds(-myTime.Millisecond);
It could be done in less code, without first assigning to myTime:
DateTime myTime = DateTime.Now.TimeOfDay.AddMilliseconds(
-DateTime.Now.TimeOfDay.Millisecond);
Although somewhat elegant, it is a bad idea. When accessing TimeOfDay twice, there is a chance that it at some point will have passed another millisecond before the second access. In that case the result would not be zero milliseconds.

If the problem is displaying it, you can do this:
DateTime.Now.ToString("HH:mm:ss")

When displaying to user you can specify needed format. Here is a good tutorial:
http://www.geekzilla.co.uk/View00FF7904-B510-468C-A2C8-F859AA20581F.htm
You can create new DateTime object passing to constructor only hour, minute, second (it's for saving.)

You can use this function to check what format suits you:
DateTime.Now.GetDateTimeFormats();
This will give you all the Formats like:
"14/05/2011"
"14/05/11"
"14.05.11"
"14-05-11"
"2011-05-14"
etc.

You can do this-
DateTime.Parse(
DateTime.Now.ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ss"),
System.Globalization.CultureInfo.CurrentCulture
);
Worked for me :).

Whats the easiest way in C# to define a time of day, i.e. HH:MM:SS, without resorting to DateTime which requires year,month,day?

I'd like to define a time of day, without necessarily specifying a year, month, day, which would require DateTime.
After I define this Time, I'd like to use all of the nice things about DateTime, i.e. AddMinutes, AddHours, .Hour, .Second, etc.
I guess what I really want the "Time" out of "DateTime", but I can't seem to find it anywhere.
Many thanks in advance!
EDIT:
This is what I was looking for:
// Specify a time of day.
TimeSpan timeSinceMidnight= new TimeSpan(16,00,00); // 4pm
... other code to calculate correct date ...
// Work out scheduled time of day.
DateTime date = new DateTime(2010,12,10).Add(timeSinceMidnight);

Why not just use the standard .NET DateTime class and ignore the date part? It seems that DateTime.ToShortTimeString() could help, or perhaps DateTime.TimeOfDay, which returns a TimeSpan representing the length of time since midnight.
Any other solution would be reinventing the wheel.

Take a look at the TimeSpan structure

Lets say you have a datetime stored somewhere such as a database or you stored it in a variable manually. To strip out the time you can use this.
string.Format("{0:MM/dd/yy}");
edit: oops you meant keep the time not the date.

C# Define begin of day of a date in another timezone

I want to define the begin of a day in another timezone with .NET/C#.
Example:
My current timezone = GMT+1
so DateTime.Today returns 19/11/2009 23:00 UTC
but actually I want to get the DateTime.Today for timezone GMT+2 which would be 19/11/2009 22:00 UTC.
How do I do this without juggling with offsets & daylightsaving calculations?

You can use TimeZoneInfo.ConvertTime. This is new in .NET 3.5.

Try:
var zone = TimeZoneInfo.GetSystemTimeZones().First(tz => tz.StandardName == DesiredTimeZoneName);
Debug.WriteLine(new DateTimeOffset(DateTime.UtcNow.Date.Ticks, zone.BaseUtcOffset).ToUniversalTime());
AFAIK, there's no other way to do this.

Update the date of a datetime object when using datetime.addhours(-1)

I have an datetime object that I want to remove one hour to display the corect time in a different time zone. I am using datetime.addhours(-1) with the -1 being a config value. This works in most cases except when I set the time to 12:59 AM today it displays 11:59 AM today. When it should display 11:59 PM. Is it possible to have addDays() repect the date?

There's a method that can help you with timezones:
TimeZoneInfo.ConvertTime(..)
Linkage

How about using the Subtract function:
DateTime.Now.Subtract(new TimeSpan(1, 0, 0));

I notice you didn't specify which framework version you are using. If you are using 2.0 SP1, 3.0 SP1, or 3.5 SP1 you might want to use the DateTimeOffset structure instead. Then you would simply specify the Timezone offset and everything should work.
Hope that helps!

Generally speaking, if you are handling time zone issues you should use the functions that store the datetime in a UTC format and then map to the correct TZ.
However if that is overkill for your application what you are doing is correect.
DateTime datetime = new DateTime( 2008,12,17,0,59, 0 );
datetime = datetime.AddHours(-1);
This results in a time of 23:59:00 or 11:59PM on 12/16/2008.
The time you are feeding in might not have the proper am/pm designator.