Develop Reference

DateTime.Now giving different formats in the same machine

I have a windows service application in which I am getting the current date and time using DateTime.Now.ToString(), which returns '04-05-2018 05:50:12'.
But I tried the same in a sample console application, but it returns the date in a different format as '5/4/2018 5:51:32 AM'
Both these machines are being executed in the same machine. Can some one let me know why is there a date format difference in these applications?

The DateTime.ToString() formats the DateTime according to current culture. As Written in the Documentation
Converts the value of the current DateTime object to its equivalent
string representation using the formatting conventions of the current
culture.(Overrides ValueType.ToString().)
If you want the same string you should instead use the DateTime.ToString(string) overload and provide the exact format which you want.
The ToString(String) method returns the string representation of a
date and time value in a specific format that uses the formatting
conventions of the current culture; for more information, see
CultureInfo.CurrentCulture.
The format parameter should contain either a single format specifier
character (see Standard Date and Time Format Strings) or a custom
format pattern (see Custom Date and Time Format Strings) that defines
the format of the returned string. If format is null or an empty
string, the general format specifier, 'G', is used.
Some uses of this method include:
Getting a string that displays the date and time in the current
culture’s short date and time format. To do this, you use the “G”
format specifier.
Getting a string that contains only the month and year. To do this,
you use the “MM/yyyy” format string. The format string uses the
current culture’s date separator.
Getting a string that contains the date and time in a specific format.
For example, the “MM/dd/yyyyHH:mm” format string displays the date and
time string in a fixed format such as “19//03//2013 18:06". The format
string uses “/” as a fixed date separator regardless of
culture-specific settings.
Getting a date in a condensed format that could be used for
serializing a date string. For example, the "yyyyMMdd" format string
displays a four-digit year followed by a two-digit month and a
two-digit day with no date separator.

Parse date time c# with correct timezone and kind

I have a datetime in database which I read using SqlDataReader and then cast it to (DateTime). After the cast its Kind property is DateTimeKind.Unspecified.
Then I have another string which I read from some other source. Its format is like this 2016-01-20T22:20:29.055Z. I do DateTime.Parse("2016-01-20T22:20:29.055Z") and its Kind property is DateTimeKind.Local.
How do I properly parse the both date times for comparison? Do I need to use DateTimeOffsets? How should I parse them?
Thanks

Because SQLReader cannot reasonably infer a DateTimeKind, it leaves it as unspecified. You'll want to use DateTime.SpecifyKind to change the DateTimeKind on your output from the SQLReader to the appropriate value. This works ok if you are only dealing with UTC and one consistent local time zone; otherwise, you really should be using DateTimeOffset in both your code and the SQL Database.
The string "2016-01-20T22:20:29.055Z" is ISO 8601 compliant and is a UTC date; however, DateTime.Parse with only 1 argument can end up performing a conversion to local time. Per the documentation:
Generally, the Parse method returns a DateTime object whose Kind
property is DateTimeKind.Unspecified. However, the Parse method may
also perform time zone conversion and set the value of the Kind
property differently, depending on the values of the s and styles
parameters:
If s contains time zone information, the date and time is converted
to the time in the local time zone and the Kind is DateTimeKind.Local.
If s contains time zone information, and styles includes the
AdjustToUniversalflag, the date and time is converted to Coordinated
Universal Time (UTC) and the Kind is DateTimeKind.Utc.
If s contains the Z or GMT time zone designator, and styles includes
the RoundtripKind flag, the date and time are interpreted as UTC and
the Kind is DateTimeKind.Utc.
Also see UTC gotchas in .NET and SQL Server in Derek Fowler's blog for additional coverage on the topic.

In your second example, 2016-01-20T22:20:29.055Z has timezone information provided with it; the 'Z' at the end indicates that the timestamp is intended for Coordinated Universal Time (UTC). However, DateTime.Parse() will default its conversion using DateTimeKind.Local unless a specific timezone is specified. You can use DateTime.ParseExact to be more specific.
As to why the datetime values in your database are coming out as Unspecified, that's likely because they contain no timezone indication at all. Check to see if your database values specify timezone information, either by using 'Z' at the end or specifying an exact timezone, such as 2016-01-20T22:20:29.055-07:00 (UTC-7).

You can use something like this:
string format = "ddd dd MMM h:mm tt yyyy";
DateTime dateTime = DateTime.ParseExact(dateString, format,
CultureInfo.InvariantCulture);
In format variable, you can put the format you want, and pass it to ParseExact function.
Hope it helps.

You are missing the datetime context (offset) in your database. You should persist it either in a datetimeoffset column or in a datetime column but persisting utc datetimes.
And always better compare two utc datetimes.

I coded a quick C# console app that I pasted in below. This converts a UTC date and time to a string (format similar to the ISO 8601 format described in another post with some extra digits of precision), writes it to a file, reads it from the file (as a string) and then converts it back to a UTC date and time.
It then compares the two UTC Date Time objects, which are both of UTC kind, and they match.
class Program
{
// "2016-01-20T22:20:29.055Z" is ISO 8601 compliant and is a UTC date
const string dtf = "yyyy-MM-ddTHH:mm:ss.fffffffZ";
static void Main(string[] args)
{
string file = #"c:\temp\file.txt";
DateTime dt = DateTime.UtcNow;
using (var sw = new System.IO.StreamWriter(file))
{
sw.WriteLine(dt.ToString(dtf, System.Globalization.CultureInfo.InvariantCulture));
}
DateTime dtin;
using (var sr = new System.IO.StreamReader(file))
{
dtin = DateTime.ParseExact(sr.ReadLine(), dtf, System.Globalization.CultureInfo.InvariantCulture);
}
Console.WriteLine(dt.ToString(dtf) + "\r\n" + dtin.ToString(dtf) + "\r\nEquality:" + (dt == dtin));
Console.ReadLine();
}
}

Parse a UTC date string to date in C#

Simple question, I have this string:
string dateString = "7/12/2014 4:42:00 PM";
This is a date string and it's in the UTC timezone.
I need to convert it to a date, so I'm doing the following:
DateTimeOffset dateOffset;
DateTimeOffset.TryParse(dateString, out dateOffset);
DateTime date = dateOffset.UtcDateTime;
The problem:
When I'm parsing the string to date, the code is considering that the dateString is in the Local Timezone of the PC (+3 GMT), and not in the UTC timezone.
So I am getting the following the dateOffset = {7/12/2014 4:42:00 PM +03:00} and thus date = {7/12/2014 1:42:00 PM}
how can I tell him that the date string provided is in the UTC format and not in the local timezone format?
Thanks

how can I tell him that the date string provided is in the UTC format and not in the local timezone format?
Specify a DateTimeStyles value of AssumeUniversal in the call. That tells the parsing code what to do. For example:
// null here means the thread's current culture - adjust it accordingly.
if (DateTimeOffset.TryParse(dateString, null, DateTimeStyles.AssumeUniversal,
out dateOffset))
{
// Valid
}
You should always use the result of TryParse to tell whether or not it's successfully parsed.
If you know the format and the specific culture, I'd personally use DateTimeOffset.TryParseExact. (Well, to be honest I'd use my Noda Time project to start with, but that's a different matter.)

There is another overload of DateTimeOffset.TryParse
DateTimeOffset.TryParse Method (String, IFormatProvider, DateTimeStyles, DateTimeOffset)
which allows you specify DateTimeStyles. One of the DateTimeStyles is AssumeUniversal, which is what you're looking for:
If no time zone is specified in the parsed string, the string is
assumed to denote a UTC. This value cannot be used with AssumeLocal or
RoundtripKind.

Don't know how .Net API provides, but I guess you could probably use ISO8601 format to indicate a UTC timezone before parsing, i.e, first translate 7/12/2014 4:42:00 PM into something 2014-07-02T16:42:00Z, then use try parse using DateTimeOffset

C# DateTime.ParseExact for "2012-09-03T06:35:31Z"

In C# I am trying to convert "2012-09-03T06:35:31Z" into a Datetime:
Date = DateTime.ParseExact( "2012-09-03T06:35:31Z", ???);
I'm not sure how to parse the rest of the function

//using System.Globalization; should be at top
Date = DateTime.ParseExact("2012-09-03T06:35:31Z", "yyyy'-'MM'-'dd'T'HH':'mm':'ss'Z'", CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal)
See the custom date and time format documentation. This is similar to the sortable format, but with a Z on the end.

You don't say whether the format is specified as always being in UTC and indicated with Z.
If that is the case, then
DateTime.ParseExact(
yourDateString, #"yyyy\-MM\-ddTHH:mm:ss\Z",
CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal)
Will do fine.
However, if UTC is not specified by the standard you are working to, the input you have to deal with could also be e.g. 2012-09-03T06:35:31+05:00 or 2012-09-03T06:35:31+0500 depending on the ISO 8601 format in use - Z is a special case within that format for +00:00. If you need to handle that possibility, then you want to first create a DateTimeOffset, and then obtain the equivalent UTC DateTime from it:
DateTimeOffset.ParseExact(yourDateString,
new string[]{#"yyyy\-MM\-ddTHH:mm:sszzz",#"yyyy\-MM\-ddTHH:mm:ss\Z"},
CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal).UtcDateTime
Note that we still use AssumeUniversal. This is because the second format is saying "A Z will appear here", but the method then ignores it, so we have to explicitly have this form interpreted as UTC. With the first format though, the zzz will give the timezone, and hence the AssumeUniversal is ignored. (Or to put it another way, it's assuming universal until told otherwise, and that format does indeed say otherwise).

Looks like you are trying to parse an Xml date. If this is the case I would suggest using the XmlConvert class...
Date = System.Xml.XmlConvert.ToDateTime("2012-09-03T06:35:31Z", XmlDateTimeSerializationMode.Local);
You will need to change the XmlDateTimeSerializationMode to the appropriate value.

getting hour part and time-zone part from datetime

I had a string in config file, defining date time with time zone.
I am not able to get this value, while reading values from config file.
In config file:
Setting name="abcdefgh" value="2012-08-10T22:00:00-08:00"
In C#, I am reading this as follows:
DateTime StartDate;
StartDate = DateTime.ParseExact(RoleEnvironment.GetConfigurationSettingValue("abcdefgh"), "yyyy-MM-dd HH:mm:ss", null);
Configuration.Instance.abcdefgh= StartDate;
In start date, i am getting 11 Aug, 2012 11:30:00, with no time zone.
I want to read it as it is. also tell, if my format of writing datetime in config file is correct

MSDN link to DateTimeOffset.
Use DateTimeOffset whenever you are referring to an exact point in
time. For example, use it to calculate "now", transaction times, file
change times, logging event times, etc. If the time zone is not
known, use it with UTC. These uses are much more common than the
scenarios where DateTime is preferred, so this should be considered
the default.
var date = DateTimeOffset.Parse("2012-08-10T22:00:00-08:00");
date.Offset // -08:00:00, offset from Coordinated Universal Time (UTC)
date.DateTime // 10/08/2012 22:00:00,

DateTime doesn't keep information about timezone. To parse the string and keep information about timezone - you should use DateTimeOffset structure.

Use the DateTimeOffset structure (and DateTimeOffset.ParseExact) if you want to store timezone information.
Your ParseExact format also doesn't quite match the setting value: it should have a zz at the end for the timezone information. You can also use DateTimeOffset.Parse since your setting string is in a standard format.

It's a standard format, so the ParseExact isn't needed, try:
StartDate = DateTime.Parse(RoleEnvironment.GetConfigurationSettingValue("abcdefgh"));
I substituted the hard-coded value you provided and got the correct result for my timezone (GMT-4) as
8/11/2012 2:00 AM
Note: as others mentioned, the timezone is not retained, so you will get the correct localized time corresponding to whatever timezone information was in the string, but you won't be able to find out what timezone that was. The DateTime.Kind property will reflect that it's a local time.