I use this code to convert my UTC string Time with format "yyyy-MM-ddTHH:mm:ssZ" to date time . for example :
string PurchaseDate == "2017-12-12T14:29:26Z";
datetime dt = DateTime.ParseExact(PurchaseDate , "yyyy-MM-ddTHH:mm:ssZ", null);
i know that PurchaseDate time is UTC time (because of "Z"). dt return {12/12/2017 5:59:26 PM} that it is my local Time(client time zone). in other word DateTime.ParseExact convert PurchaseDate to my client time zone! my question is how this method know my client TimeZone ? is it recommend to use this for global application and show user time zone at all ??
Update My question:
sometime for implement timezone management in my global website i google it for possible souloution and I find this Use ful link :
How to display dates and times in clients timezone
after month i found we can use TimeZoneInfo.Local for finding cliend TimeZone !
so should i say that link is useless? I want to know if there is a simple way to find client time zone in dotNet BackEnd code so why this complex way is Used ??
... how this method know my client TimeZone?
It doesn't understand anything about a "client". It just has the local time of wherever the code is running. If the code is running on a user's desktop computer or mobile device, then it's the time zone of that device.
If the code is running on a server, then it uses the time zone of the server. You should avoid this in general, as the server's time zone is usually irrelevant to your application or users. This applies to TimeZoneInfo.Local as well.
If you want to parse your string as UTC DateTime, then you'll need to pass an argument that tells the parser not to convert to local time:
string PurchaseDate = "2017-12-12T14:29:26Z";
DateTime dt = DateTime.ParseExact(PurchaseDate, "yyyy-MM-ddTHH:mm:ssK",
CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind);
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("...you'll need to decide...");
DateTime clientDateTime = TimeZoneInfo.ConvertTimeFromUtc(dt, tz);
In the above, I use DateTimeStyles.RoundtripKind, which says to evaluate the string for it's offset (Z in this case) and decide whether to use Utc, Local, or Unspecified kind on the resulting DateTime. Also note that you should use K in the format string, not Z.
A better approach would be to use DateTimeOffset instead of DateTime, in which case the Z will automatically set an offset of +00:00.
You'll still need to figure out what time zone to convert to, regardless of which approach you take. If you happen to be writing code that runs on the user's device, then you get the benefit of having TimeZoneInfo.Local predetermined for you. Otherwise you do not.
Related
We are developing a C# application for a web-service client. This will run on Windows XP PC's.
One of the fields returned by the web service is a DateTime field. The server returns a field in GMT format i.e. with a "Z" at the end.
However, we found that .NET seems to do some kind of implicit conversion and the time was always 12 hours out.
The following code sample resolves this to some extent in that the 12 hour difference has gone but it makes no allowance for NZ daylight saving.
CultureInfo ci = new CultureInfo("en-NZ");
string date = "Web service date".ToString("R", ci);
DateTime convertedDate = DateTime.Parse(date);
As per this date site:
UTC/GMT Offset
Standard time zone: UTC/GMT +12 hours
Daylight saving time: +1 hour
Current time zone offset: UTC/GMT +13 hours
How do we adjust for the extra hour? Can this be done programmatically or is this some kind of setting on the PC's?
For strings such as 2012-09-19 01:27:30.000, DateTime.Parse cannot tell what time zone the date and time are from.
DateTime has a Kind property, which can have one of three time zone options:
Unspecified
Local
Utc
NOTE If you are wishing to represent a date/time other than UTC or your local time zone, then you should use DateTimeOffset.
So for the code in your question:
DateTime convertedDate = DateTime.Parse(dateStr);
var kind = convertedDate.Kind; // will equal DateTimeKind.Unspecified
You say you know what kind it is, so tell it.
DateTime convertedDate = DateTime.SpecifyKind(
DateTime.Parse(dateStr),
DateTimeKind.Utc);
var kind = convertedDate.Kind; // will equal DateTimeKind.Utc
Now, once the system knows its in UTC time, you can just call ToLocalTime:
DateTime dt = convertedDate.ToLocalTime();
This will give you the result you require.
I'd look into using the System.TimeZoneInfo class if you are in .NET 3.5. See http://msdn.microsoft.com/en-us/library/system.timezoneinfo.aspx. This should take into account the daylight savings changes correctly.
// Coordinated Universal Time string from
// DateTime.Now.ToUniversalTime().ToString("u");
string date = "2009-02-25 16:13:00Z";
// Local .NET timeZone.
DateTime localDateTime = DateTime.Parse(date);
DateTime utcDateTime = localDateTime.ToUniversalTime();
// ID from:
// "HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Time Zone"
// See http://msdn.microsoft.com/en-us/library/system.timezoneinfo.id.aspx
string nzTimeZoneKey = "New Zealand Standard Time";
TimeZoneInfo nzTimeZone = TimeZoneInfo.FindSystemTimeZoneById(nzTimeZoneKey);
DateTime nzDateTime = TimeZoneInfo.ConvertTimeFromUtc(utcDateTime, nzTimeZone);
TimeZone.CurrentTimeZone.ToLocalTime(date);
DateTime objects have the Kind of Unspecified by default, which for the purposes of ToLocalTime is assumed to be UTC.
To get the local time of an Unspecified DateTime object, you therefore just need to do this:
convertedDate.ToLocalTime();
The step of changing the Kind of the DateTime from Unspecified to UTC is unnecessary. Unspecified is assumed to be UTC for the purposes of ToLocalTime: http://msdn.microsoft.com/en-us/library/system.datetime.tolocaltime.aspx
I know this is an older question, but I ran into a similar situation, and I wanted to share what I had found for future searchers, possibly including myself :).
DateTime.Parse() can be tricky -- see here for example.
If the DateTime is coming from a Web service or some other source with a known format, you might want to consider something like
DateTime.ParseExact(dateString,
"MM/dd/yyyy HH:mm:ss",
CultureInfo.InvariantCulture,
DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal)
or, even better,
DateTime.TryParseExact(...)
The AssumeUniversal flag tells the parser that the date/time is already UTC; the combination of AssumeUniversal and AdjustToUniversal tells it not to convert the result to "local" time, which it will try to do by default. (I personally try to deal exclusively with UTC in the business / application / service layer(s) anyway. But bypassing the conversion to local time also speeds things up -- by 50% or more in my tests, see below.)
Here's what we were doing before:
DateTime.Parse(dateString, new CultureInfo("en-US"))
We had profiled the app and found that the DateTime.Parse represented a significant percentage of CPU usage. (Incidentally, the CultureInfo constructor was not a significant contributor to CPU usage.)
So I set up a console app to parse a date/time string 10000 times in a variety of ways. Bottom line:
Parse() 10 sec
ParseExact() (converting to local) 20-45 ms
ParseExact() (not converting to local) 10-15 ms
... and yes, the results for Parse() are in seconds, whereas the others are in milliseconds.
I'd just like to add a general note of caution.
If all you are doing is getting the current time from the computer's internal clock to put a date/time on the display or a report, then all is well. But if you are saving the date/time information for later reference or are computing date/times, beware!
Let's say you determine that a cruise ship arrived in Honolulu on 20 Dec 2007 at 15:00 UTC. And you want to know what local time that was.
1. There are probably at least three 'locals' involved. Local may mean Honolulu, or it may mean where your computer is located, or it may mean the location where your customer is located.
2. If you use the built-in functions to do the conversion, it will probably be wrong. This is because daylight savings time is (probably) currently in effect on your computer, but was NOT in effect in December. But Windows does not know this... all it has is one flag to determine if daylight savings time is currently in effect. And if it is currently in effect, then it will happily add an hour even to a date in December.
3. Daylight savings time is implemented differently (or not at all) in various political subdivisions. Don't think that just because your country changes on a specific date, that other countries will too.
#TimeZoneInfo.ConvertTimeFromUtc(timeUtc, TimeZoneInfo.Local)
Don't forget if you already have a DateTime object and are not sure if it's UTC or Local, it's easy enough to use the methods on the object directly:
DateTime convertedDate = DateTime.Parse(date);
DateTime localDate = convertedDate.ToLocalTime();
How do we adjust for the extra hour?
Unless specified .net will use the local pc settings. I'd have a read of: http://msdn.microsoft.com/en-us/library/system.globalization.daylighttime.aspx
By the looks the code might look something like:
DaylightTime daylight = TimeZone.CurrentTimeZone.GetDaylightChanges( year );
And as mentioned above double check what timezone setting your server is on. There are articles on the net for how to safely affect the changes in IIS.
In answer to Dana's suggestion:
The code sample now looks like:
string date = "Web service date"..ToString("R", ci);
DateTime convertedDate = DateTime.Parse(date);
DateTime dt = TimeZone.CurrentTimeZone.ToLocalTime(convertedDate);
The original date was 20/08/08; the kind was UTC.
Both "convertedDate" and "dt" are the same:
21/08/08 10:00:26; the kind was local
I had the problem with it being in a data set being pushed across the wire (webservice to client) that it would automatically change because the DataColumn's DateType field was set to local. Make sure you check what the DateType is if your pushing DataSets across.
If you don't want it to change, set it to Unspecified
I came across this question as I was having a problem with the UTC dates you get back through the twitter API (created_at field on a status); I need to convert them to DateTime. None of the answers/ code samples in the answers on this page were sufficient to stop me getting a "String was not recognized as a valid DateTime" error (but it's the closest I have got to finding the correct answer on SO)
Posting this link here in case this helps someone else - the answer I needed was found on this blog post: http://www.wduffy.co.uk/blog/parsing-dates-when-aspnets-datetimeparse-doesnt-work/ - basically use DateTime.ParseExact with a format string instead of DateTime.Parse
This code block uses universal time to convert current DateTime object then converts it back to local DateTime. Works perfect for me I hope it helps!
CreatedDate.ToUniversalTime().ToLocalTime();
I am trying do to something like this:
On a client side I have datepicker for selecting date, drop down for selecting an hour, and drop down with time zones for selecting user time zone.
I am sending this info to server. On a server side, I want to accomplish this:
Take date and time values, and check what is the value of time zone.
If it is for example "UTC+1" (or any other +- value of UTC time), convert that into UTC, before saving.
What I am not sure how to do it is: What value should I send from client as time zone information so server can detect it is a for example UTC+1.
I saw examples like this:
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");
On how to find out what is the time zone by its id, but I cannot do something like this:
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("UTC+1");
Because, I get an exception, of course:
Additional information: The time zone ID 'UTC+1' was not found on the
local computer.
Does someone know what is Id for all UTC+-someNumber, or there is a way to detect timezone from UTC string in some different way?
Did someone had experience whit this kind of a conversion?
As far as I remember the only way to work with the timezones is by the full name that is available in your OS.
You can find a similar question here.
A list from MSDN is here.
So there seems to be no easy way to convert strings like "UTC+1", unless you create a mapping to the ones that are supported by framework.
You could use TimeZoneInfo.CreateCustomTimeZone():
DateTime utcTime = DateTime.UtcNow;
TimeZoneInfo targetTimeZone = TimeZoneInfo.CreateCustomTimeZone("MyId", TimeSpan.FromHours(1), "Somewhere", "Somewhere");
DateTime targetTime = TimeZoneInfo.ConvertTime(utcTime, targetTimeZone);
or you can use DateTimeOffset, or DateTime.AddHours(1):
var datetimeOffset = new DateTimeOffset(yourDateTime, TimeSpan.FromHours(1));
var otherDatetime = yourDateTime.AddHours(1);
I am trying to figure out the best way of letting the users set the internal DateTime value of the Portable Class Library based on some string parameter they provide. The string parameter has to be a simple format.
So, now I have some considerations.
Is specifying UTC Offset enough for getting the right DateTime
public static DateTime FromUtcOffset(string value)
{
var utcDateTime = DateTime.UtcNow;
var offSet = TimeSpan.Parse(value);
return utcDateTime + offSet;
}
Or is specifying the TimeZone has some advantage over UTC Offset
TimeZoneInfo someTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");
DateTime convertTimeFromUtc = TimeZoneInfo.ConvertTimeFromUtc(utcDateTime, someTimeZone);
My question is: What would be the right string parameter that can be taken from the user to let him decide what the value of DateTime would be?
Utc Offset
TimeZone
Or any other alternative that's less verbose.
Actually, it depends:
Do you work with network hosts, located in different time zones
Do you store time values for using them in future
Does your library work locally (hence, knows user's timezone)
1+2 basically mean if your time offset might change. If it not (the library is intended for local use only), get local time and don't care about the time offset. However, if the offset might change, usually storing "absolute" time in UTC format should be enough. To do this, you can:
Ask user for UTC time, not their local time
or
Ask for local time + offset (or get the offset from the local time zone, if possible)
Convert it to UTC time and store/process in UTC time
Provide output using local time (using the offset from 1. if it didn't change)
In 1 and 3 you will need a timezone to figure out the time offset. You don't need to know timezone if you already know the offset. Moreover, DateTime itself can store time offset information. It also can tell you if it stores local or UTC time (see DateTime.Kind Property).
I've been using DateTime.Now in my asp.net application. However, I think this is always using the time of the server which is in the US. How could I get the datetime based on the timezone? For example, if someone is using my software in Taiwan I would want to show the date based on their timezone not on US timezone.
I know that I can find the current timezone like this:
TimeZone localZone = TimeZone.CurrentTimeZone;
However, I need a DateTiem. Is there a way I could convert this to a DateTime?
Edit
To clarify, I want to just show the current date on my webpage. However, when I use DateTime.Now it uses the timezone of my server. I won't be storing this date in my DB so I don't think I'll need this date in UTC.
This will convert local time, to specific time zone:
var yourTime = TimeZoneInfo.ConvertTime(DateTime.Now, TimeZoneInfo.Local, TimeZoneInfo.FindSystemTimeZoneById("your time zone ID"));
I've string (variable is fileDate) with Date values in the following format:
2/12/2011 11:58 AM
Now I want to convert this to a date and then to UTC time based as I've problems in comparing dates in different machines, so *I always want to convert all strings (which are getting compared) to Utc_date values.*
I tried this code below but it did not work as I'm not able to convert the above string to Datetime based (as it does not have seconds).
DateTime date = Convert.ToDateTime(fileDate);
date = DateTime.SpecifyKind(date, DateTimeKind.Utc);
fileDate = date.ToString("MM/dd/yyyy hh:mm tt");
Above did not work showing FormatException.
Can you pl help?
To start with, I'd suggest using DateTime.ParseExact or TryParseExact - it's not clear to me whether your sample is meant to be December 2nd or February 12th. Specifying the format may well remove your FormatException.
The next problem is working out which time zone you want to convert it with - are you saying that 11:58 is a local time in some time zone, or it's already a UTC time?
If it's a local time in the time zone of the code which is running this, you can use DateTimeStyles.AssumeLocal | DateTimeStyles.AdjustToUniversal to do it as part of parsing.
If it's already a universal time, use DateTimeStyles.AssumeUniversal
If it's a local time in a different time zone, you'll need to use TimeZoneInfo to perform the conversion.
Also, if it's a local time you'll need to consider two corner cases (assuming you're using a time zone which observes daylight saving time):
A local time may be skipped due to DST transitions, when the clocks go forward. So if the clocks skip from 1am to 2am, then 1:30am doesn't exist at all.
A local time may be ambiguous due to DST transitions, when the clocks go back. So if the clocks go back from 2am to 1am, then 1:30am occurs twice at different UTC times - which occurrence are you interested in?
You should decide how you want to handle these cases, and make sure they're covered in your unit tests.
Another option is to use my date and time library, Noda Time, which separates the concepts of "local date/time" and "date/time in a particular time zone" (and others) more explicitly.
you should be using DateTime.ParseExact to get the value into a proper DateTime instance, and then you can use .ToUniversalTime() to get the UTC time (this would be with respect to the difference of time as in your server machine)
you can use :
DateTime.Now.ToUniversalTime();
i don't mean to say to you should use "DateTime.Now" but you get the point that as a part of the DateTime object you have a method to transform it to Universal time
http://msdn.microsoft.com/en-us/library/system.datetime.touniversaltime.aspx