Conversion of a UTC date/time string in C#

问题:

I need to convert the string "Fri Sep 11 00:00:00 GMT+04:00 2020" into a DateTime object 11.09.2011.

When I use

DateTime result;
DateTime.TryParseExact(MyString, "ddd MMM dd HH:mm:ss 'GMT'zzz yyyy", 
    CultureInfo.InvariantCulture, DateTimeStyles.None, out result);

result is equal to {9/10/2020 11:00:00 PM}.

How can I modify the code so that the date component is 11.09.2011 and not 10.09.2011 (I only need the date and don't care about the time) ?

回答1:

Parse into a DateTimeOffset instead, given that you've got an offset. From the documentation of the zz specifier that you're using:

With DateTime values, the "zz" custom format specifier represents the signed offset of the local operating system's time zone from UTC, measured in hours. It does not reflect the value of an instance's DateTimeKind property. For this reason, the "zz" format specifier is not recommended for use with DateTime values.

So you'd end up with:

DateTimeOffset result;
bool success = DateTimeOffset.TryParseExact
         (text, "ddd MMM dd HH:mm:ss 'GMT'zzz yyyy", 
          CultureInfo.InvariantCulture, DateTimeStyles.None, out result);

From there, you can take the DateTime part, which will be midnight on September 11th.

If you want just a date, you could use my Noda Time project to create a LocalDate:

LocalDate = OffsetDateTime.FromDateTimeOffset(result).LocalDateTime.Date;

(I'd love to suggest parsing directly to OffsetDateTime, but we haven't got support for that yet. We're hoping to include it in version 1.2.)

回答2:

C# does not have a pure Date type.
If you don't care about the time, just ignore that portion of the DateTime.

If you want the time to always be midnight, use the .Date property, which will return a DateTime with the same date but at midnight.