datetime to string with time zone

Question

I have a DateTime stored in universal time (UTC) of value 2010-01-01 01:01:01.

I would like to display it in EST in this format 2010-01-01 04:01:01GMT-04:00, however the 'K' formatter for timezone doesn't work in ToString

Allodium

Do you have the time in universal time (UTC) or Greenwich Mean Time (GMT)? – Became

If you use the 'K' as a part of your formatter string on DateTime.UtcNow, it doesn't show the offset, because you're already on the GMT timezone and instead 'Z' is appended to your string. But, if you call it on a local time, it shows the offset correctly. The code for ISO8601 format would be DateTime.Now.ToString("yyyy-MM-dd'T'HH:mm:ss.fff'GMT'K", CultureInfo.InvariantCulture) – Beggs

Answer 1

Use the "zzz" format specifier to get the UTC offset. For example:

        var dt = new DateTime(2010, 1, 1, 1, 1, 1, DateTimeKind.Utc);
        string s = dt.ToLocalTime().ToString("yyyy-MM-dd HH:mm:ss \"GMT\"zzz");
        Console.WriteLine(s);

Output: 2009-12-31 19:01:01 GMT-06:00

I'm in the CDT timezone. Make sure the DateTime is unambiguously DateTimeKind.Utc.

Alameda

Keep in mind that all "zzz" does is tack the current environment's timezone offset on the end of the datetime being formatted. It does NOT take into account the DateTimeKind value set for the DateTime. It works for this particular case, but if you're formatting a UTC date, it likely won't turn out like you planned. – Ligature

Answer 2

If like myself you happen to need a format like 2018-03-31T01:23:45.678-0300 (no colon in the timezone part), you can use this:

datetime.ToString("yyyy-MM-ddTHH:mm:ss.fffzzz").Remove(26,1)

Audi

This is quite similar to IS08601 format, for which you can likely just use the O format specifier (O includes the colon and seems to have microsecond precision by default) – Vasoinhibitor

Right, that format is exactly like "yyyy-MM-ddTHH:mm:ss.fffffffzzz". – Audi

Answer 3

This method will return the specified time in Eastern Standard Time (as the question requested), even if EST is not the local time zone:

public string GetTimeInEasternStandardTime(DateTime time)
{
    TimeZoneInfo easternStandardTime = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
    DateTimeOffset timeInEST = TimeZoneInfo.ConvertTime(time, easternStandardTime);
    return timeInEST.ToString("yyyy-MM-dd hh:mm:ss tt\" GMT\"zzz");
}

Note: I haven't tested this in a non-English OS. See the MSDN documentation on TimeZoneInfo.FindSystemTimeZoneById.

Schwarzwald

@Blakely That's a good point, this answer before didn't disambiguate between AM and PM. I added the "tt" to the time format string to add the AM/PM. Per your comment, you could alternatively replace "hh" with "HH" to output the hours using a 24-hour clock (from 00 to 23). – Schwarzwald

Answer 4

Something like this works. You could probably clean it up a bit more:

string newDate = string.Format("{0:yyyy-MM-dd HH:mm:ss} GMT {1}", dt.ToLocalTime(), dt.ToLocalTime().ToString("%K"));

Sheepshead

You, probably, meant HH, not hh. – Blakely

Probably... the "hh" gives the 12-hour-clock result where "HH" gives the military-time result. – Sheepshead

Robaticus, I meant that 12-hour format is incompatible with the rest of your answer, because you don't specify AM/PM. I.e. either t/tt should be added to make hh meaningful (e.g. 02:00 AM, 03:00 PM), or hh should be replaced with HH to produce 24-hour format (e.g. 02:00, 15:00). So the yyyy-MM-dd hh:mm:ss format produces ambiguous output that can't be decoded back :(. – Blakely

I agree. I'll modify my answer to have the caps... though it is probably a low value change, since the selected answer has "HH" – Sheepshead

Answer 5

I think you are looking for the TimeZoneInfo class (see http://msdn.microsoft.com/en-us/library/system.timezoneinfo_members.aspx). It has many static methods to convert dates between time zones.

Keg

Answer 6

If you use the "zzz" format specifier give you the local time zone offset from UTC, but if you want have the specific time zone offset from UTC you should using ToOffset method.
see more here

The ToOffset method is an alternative to calling the TimeZoneInfo.ConvertTime(DateTimeOffset, TimeZoneInfo) method. It can be useful for performing simple conversions from one time zone to another when the time zones' offsets from Coordinated Universal Time (UTC) are known.

For example

    Console.WriteLine("Local time zone :" + DateTime.Now.ToString("yyyy-MM-ddTHH:mm:sszzz"));
    Console.WriteLine("Iran time zone :" + ((DateTimeOffset)DateTime.Now).ToOffset(TimeZoneInfo.FindSystemTimeZoneById("Iran Standard Time").BaseUtcOffset).ToString("yyyy-MM-ddTHH:mm:sszzz"));
    Console.WriteLine("Eastern time zone :" + ((DateTimeOffset)DateTime.Now).ToOffset(TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time").BaseUtcOffset).ToString("yyyy-MM-ddTHH:mm:sszzz"));

    //Outputs
    Local time zone :2024-06-21T01:41:15+03:30
    Iran time zone :2024-06-21T01:41:15+03:30
    Eastern time zone :2024-06-20T17:11:15-05:00

In the example above, the output of the first line may change by changing the Local TimeZone setting, but the output of the next two lines is always the same and based on the specific given time zone.

Minette