How to parse and generate DateTime objects in ISO 8601 format

Question

There is this SOAP web service that sends me datetime objects in the following format

2016-03-29T12:20:35.093-05:00

That is day 29 of March of year 2016. Hour: 12:20:35.093 (GMT-5).

I want to be able to create a DateTime object, like this:

DateTime.Now

and get the string representation in the format described above and also the inverse operation, create a DateTime from a string like the one given above.

I've tried the following in order to create the date:

new DateTime(2016, 3, 29, 12, 20, 35, 093, DateTimeKind.Utc)

However, I can't not see how to specifie GMT-5 there...

I don't know how to convert a DateTime to the specified string format, either.

Using Nate's code I'm doing the following:

var d = new DateTimeOffset(2016, 3, 29, 12, 20, 35, 93, TimeSpan.FromHours(-3));

FormatIso8601(d)

However this call is returning: "2016-03-29T15:20:35Z" instead of :

"2016-03-29T12:20:35.093-03:00"

which is what I actually need.

I think this works:

        d.ToString("yyyy-MM-ddTHH:mm:ss.fffzzz")

Yes, but I couldnt find the way to do it at all. Otherwise I wouldn't have come here to ask — Stephen H. Anderson, Mar 30 '16 at 16:00
Possible duplicate of [C# Parse Date/Time with a unique format I haven't seen before](http://stackoverflow.com/questions/5411322/c-sharp-parse-date-time-with-a-unique-format-i-havent-seen-before) — workabyte, Mar 30 '16 at 16:08

Nate Barbettini · Accepted Answer · 2016-03-30T17:06:31.983

29

The format you're describing is ISO 8601.

Since you're working with timestamps that inclulde a time zone component, I'd strongly recommend using DateTimeOffset instead of DateTime. It makes things so much easier!

To create a DateTimeOffset for a given date, time, and time zone offset, use this syntax:

var date = new DateTimeOffset(2016, 3, 29, 12, 20, 35, 93, TimeSpan.FromHours(-5));
// March 29, 2016 at 12:20:35.93 GMT-5

This code will format a DateTimeOffset as ISO 8601:

public static string FormatIso8601(DateTimeOffset dto)
{
    string format = dto.Offset == TimeSpan.Zero
        ? "yyyy-MM-ddTHH:mm:ss.fffZ"
        : "yyyy-MM-ddTHH:mm:ss.fffzzz";

    return dto.ToString(format, CultureInfo.InvariantCulture);
}

And, to parse a string back to a DateTimeOffset:

public static DateTimeOffset ParseIso8601(string iso8601String)
{
    return DateTimeOffset.ParseExact(
        iso8601String,
        new string[] { "yyyy-MM-dd'T'HH:mm:ss.FFFK" },
        CultureInfo.InvariantCulture,
        DateTimeStyles.None);
}

If you must get back to a DateTime you can get this from the DateTimeOffset.UtcDateTime property.

edited Mar 30 '16 at 17:06

answered Mar 30 '16 at 16:08

Nate Barbettini

51,256
26
134
147

Thanks a lot. Is it safe to do this? ParseIso8601(myDate).DateTime to obtain a datetime object? In my system I would need datetimes instead of datetimeoffsets, if possible. Thanks – Stephen H. Anderson Mar 30 '16 at 16:26
It's possible, but beware of unintended side effects: the time you get will depend on the local time zone of your machine. UtcDateTime will always return a UTC time, if you want to avoid that conversion. – Nate Barbettini Mar 30 '16 at 16:29
1

So it's impossible to obtaina DateTime object which represents the same exact time I passed in the string to ParseIso8601? – Stephen H. Anderson Mar 30 '16 at 16:30
"Exact time" in which time zone? The string may represent a different time zone than your machine is in. – Nate Barbettini Mar 30 '16 at 16:31
Sure - UtcDateTime will be unambiguous. – Nate Barbettini Mar 30 '16 at 16:32
If I do this: var date = new DateTimeOffset(2016, 3, 29, 12, 20, 35, 93, TimeSpan.FromHours(-5)); and then I do date.DateTime would it still be in GMT-5? – Stephen H. Anderson Mar 30 '16 at 16:32
This is why `DateTime` sucks. :( It would not necessarily still be GMT-5, it would depend on the time zone of your machine. If your machine is also GMT-5, then yes. – Nate Barbettini Mar 30 '16 at 16:33
No problem. If possible, it's highly recommended to switch everything over to `DateTimeOffset`. – Nate Barbettini Mar 30 '16 at 16:35
Nate, I have a problem with the code given. Please see my edit (I'm publishing it in 5 minutes) – Stephen H. Anderson Mar 30 '16 at 16:53

score 23 · Answer 2 · answered Oct 13 '16 at 09:58

A simpler way is to use the ToString method on DateTimeOffset with the "o" argument. This automatically prints the date in ISO8601 format

DateTimeOffset.Now.ToString("o");

The static parse method is also capable of correctly parsing a date in ISO8601 format.

DateTimeOffset.Parse("2016-25-12T20:45:30.3124+01:00");
DateTimeOffset.Parse("2016-25-12T20:45:30.3124Z");

score 1 · Answer 3 · answered Oct 25 '17 at 13:53

1

Simple answer: DateTime.UtcNow.ToString("o")

answered Oct 25 '17 at 13:53

Tim P.

2,903
24
26

How to parse and generate DateTime objects in ISO 8601 format

3 Answers3

Linked

Related