How to convert string offset to timespan in c# - c#

I'm trying to convert the convert time to the user's time zone, but I don't have the windows time zone string such as "Pacific Standard Time". All I have is a string offset such as "-07:00". Looks like I need to create a timespan. Is the only way to parse this string manually?. Seems like there should be a way to convert a time using a string offset, but maybe I am missing something.
I have this but it requires the timezone. I'm trying to modify it to use the offset instead, but you can see the timespan that is created for the conversion and I need to get my offset to the timespan.
static void Main(string[] args)
{
var currentTimeInPacificTime = ConvertUtcTimeToTimeZone(DateTime.UtcNow, "Pacific Standard Time");
//TimeSpan ts = new TimeSpan("-07:00");
Console.ReadKey();
}
static DateTimeOffset ConvertUtcTimeToTimeZone(DateTime dateTime, string toTimeZoneDesc)
{
if (dateTime.Kind != DateTimeKind.Utc) throw new Exception("dateTime needs to have Kind property set to Utc");
TimeSpan toUtcOffset = TimeZoneInfo.FindSystemTimeZoneById(toTimeZoneDesc).GetUtcOffset(dateTime);
var convertedTime = DateTime.SpecifyKind(dateTime.Add(toUtcOffset), DateTimeKind.Unspecified);
return new DateTimeOffset(convertedTime, toUtcOffset);
}

You can just use the TimeSpan.Parse method:
TimeSpan ts = TimeSpan.Parse("-07:00");
Console.WriteLine(ts); // -07:00:00
Be careful to strip a leading "+" as TimeSpan.Parse will fail here. "+01:00" is incorrect, but "01:00" works.
Or if you want be a little more safe, try the TimeSpan.TryParse method:
TimeSpan ts;
if (TimeSpan.TryParse("-07:00", out ts))
Console.WriteLine(ts); // -07:00:00
But of course if all you want to do is convert a UTC date/time to a local date/time, you can just do this:
DateTime localDateTime = utcDateTime.ToLocalTime();
Or to convert it to any timezone:
TimeZoneInfo tzi = TimeZoneInfo.FindSystemTimeZoneById(toTimeZoneDesc);
DateTime localDateTime = TimeZoneInfo.ConvertTime(utcDateTime, tzi);

For more complicated/non-standard formats you can also use TimeSpan.ParseExact(String, String, IFormatProvider), where the second String is a Custom TimeSpan Format String.
API information is available at msdn.microsoft.com, and is linked above.linked.

I'm trying to convert the convert time to the user's time zone, but I don't have the windows time zone string such as "Pacific Standard Time". All I have is a string offset such as "-07:00".
Then you don't have what you need to make the correct conversion. Read "Time Zone != Offset" in the timezone tag wiki.
It is important to understand that the "Pacific Standard Time" value is the .Id for the TimeZoneInfo object that is used for US Pacific Time. It covers both Pacific Standard Time (UTC-8) and Pacfic Daylight Time (UTC-7).
All I have is a string offset such as "-07:00". Looks like I need to create a timespan.
Now you have what is commonly called the XY Problem. You shouldn't have any need to work with the offset by itself.
In your code, there is a call to dateTime.Add(toUtcOffset). When doing time zone conversions, this is a code smell that you are doing it wrong. You should never have to manually add or subtract time just to manipulate time zones. That should be reserved for actually changing the moment in time you are talking about.
What you should be doing is to collect a real time zone id from your user. Either "Pacific Standard Time" for use with TimeZoneInfo, or "America/Los_Angeles" for use with a TZDB implementation like Noda Time.
If time zone conversions aren't important in your context, then you might just want to collect a full DateTimeOffset value such as 2013-08-17T13:27:00.000-07:00 instead.

There are time zone strings which includes "Pacific Standard Time". The complete list can be found here. http://www.xiirus.net/articles/article-_net-convert-datetime-from-one-timezone-to-another-7e44y.aspx
Any DateTime object can be converted to some timezone -
TimeZoneInfo timeZoneInfo;
DateTime dateTime ;
//Set the time zone information to Pacific Standard Time
timeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");
//Get date and time in US Mountain Standard Time
dateTime = TimeZoneInfo.ConvertTime(DateTime.Now, timeZoneInfo);
//Print out the date and time
Console.WriteLine(dateTime.ToString("yyyy-MM-dd HH-mm-ss"));
So you method can be modified as -
static DateTimeOffset ConvertUtcTimeToTimeZone(DateTime dateTime, string toTimeZoneDesc)
{
return new DateTimeOffset(TimeZoneInfo.ConvertTime(dateTime, TimeZoneInfo.FindSystemTimeZoneById(toTimeZoneDesc)));
}

Related

How to parse time into DateTimeOffset in a specific time zone?

Given the 11:00 PM, and knowing that the server is running using UTC time, I need to take that time parse it into a DateTimeOffset from a specific TimeZone.
For example if the docker container's time running the server is 2:00 AM 6/3/2022, I need to be able to check if current date time now in 'Eastern Standard Time' zone, is past 6/2/2022 11:00 PM or before.
To get localized DateTime now I have the following code which works as expected:
TimeZoneInfo tzInfo = TimeZoneInfo.FindSystemTimeZoneById(zoneId);
DateTime nowLocalTime = TimeZoneInfo.ConvertTime(DateTime.Now, tzInfo);
DateTimeOffset targetDateTimeOffset =
new DateTimeOffset(nowLocalTime,
tzInfo.GetUtcOffset
(
DateTime.SpecifyKind(nowLocalTime, DateTimeKind.Local)
));
I thought I had it figured out for parsing the time into DateTime and then getting the specific DateTimeOffset object, until it hit past midnight on the server. Since the server's time is now 12:01 AM 6/3/2022 when I run the following code:
string timeOfDay = "11:00 AM";
TimeZoneInfo tzInfo = TimeZoneInfo.FindSystemTimeZoneById(zoneId);
DateTime.TryParse(timeOfDay, out DateTime dateTime);
DateTimeOffset targetDateTimeOffset =
new DateTimeOffset
(
dateTime,
tzInfo.GetUtcOffset
(
DateTime.SpecifyKind(dateTime,
DateTimeKind.Local)
)
);
This now returns 6/3/2022 11:00PM. This makes sense but I need to get DateTimeOffset parsed into the specified TimeZone. Because right now in 'Eastern Standard Time' zone it is 6/2/2022 not 6/3/2022. So basically I need to take 11:00 PM parse it into DateTimeOffset of the provided TimeZone, is that possible?
The .net DateTime type was designed before the age of cloud computing. Where you only had to worry about the machine's .Local time or .Utc. IMHO DateTimeKind.Unspecified should be marked [Obsolete] and any API behaviour which relies on it should instead throw an exception.
TimeZoneInfo.ConvertTime(DateTime, TimeZoneInfo) is a particularly strange function. If you pass a DateTimeKind.Unspecified, or a TimeZoneInfo other than TimeZoneInfo.Local or TimeZoneInfo.Utc, the result is essentially unusable.
IMHO you're better off pushing the problem of parsing and displaying date / time values to the client. Force the client to parse any date time strings in their local timezone. Then either use UTC everywhere, or use DateTimeOffset to store the timezone explicitly.
It's easy enough to get the current time in a specific timezone;
TimeZoneInfo tzInfo = TimeZoneInfo.FindSystemTimeZoneById(zoneId);
DateTimeOffset tzLocalTime = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, tzInfo);
Unfortunately while you can parse a string and .AssumeLocal or .AssumeUniversal, anything else is barely supported or documented. While you can provide a CultureInfo for parsing non-gregorian calendars, there's no DateTimeOffset.Parse which takes a default TimeZoneInfo parameter. The closest I've found is to check if the string contains an offset, based on this question.
static DateTimeOffset ParseAsDateTimeOffset(string s, TimeZoneInfo defaultTimeZone, CultureInfo culture = null)
{
if (Regex.IsMatch(s, #"(Z|[+-]\d{2}:\d{2})$"))
return DateTimeOffset.Parse(s, culture ?? CultureInfo.InvariantCulture);
var dt = DateTime.Parse(s, culture ?? CultureInfo.InvariantCulture);
return new DateTimeOffset(dt, defaultTimeZone.GetUtcOffset(dt));
}
While this works for most of the year, I'm not certain if it works properly for time values around DST adjustments. But without an explicit offset, those values are going to be wrong anyway.

How to get DateTime from UTC offset

I am trying to figure out how to get a DateTime instance using an UTC offset value, i have to get the DateTime of the desired UTC offset regardless of which UTC the current system is.
All posts i've seen are about getting the UTC string data from a DateTime, also i've seen that there is a post that says how to get the other DateTime by calculating the difference using the current DateTime, that doesn't seem to work well since i need the code to be working regardless of which UTC the system is using.
What i have tried this far:
public static void Main(string[] args) {
DateTime utcDateTime = DateTime.UtcNow;
TimeSpan offSet = TimeSpan.FromHours((double)-4.00); // UTC-4
DateTime newDateTime = utcDateTime.Add(offSet);
Console.WriteLine(newDateTime);
}
This is something i saw in a different post but it looks that it only changes the hour in a wrong way.. please help.
To get the current time in a particular offset (such as UTC-4), as a DateTime, the easiest way (IMHO) is:
DateTime dt = DateTimeOffset.UtcNow.ToOffset(TimeSpan.FromHours(-4)).DateTime;
Another (messier) way to get the same results would be:
DateTime dt = DateTime.SpecifyKind(DateTime.UtcNow.AddHours(-4), DateTimeKind.Unspecified);
One might also just keep it as a DateTimeOffset, such that the offset from UTC is not lost.
DateTimeOffset dto = DateTimeOffset.UtcNow.ToOffset(TimeSpan.FromHours(-4));
Or the messier way:
TimeSpan offset = TimeSpan.FromHours(-4);
DateTime dt = DateTime.SpecifyKind(DateTime.UtcNow.Add(offset), DateTimeKind.Unspecified);
DateTimeOffset dto = new DateTimeOffset(dt, offset);
However, in most cases, one is probably not working with a fixed offset, but is instead looking for the time in a particular time zone, which could be in a variety of different offsets depending on the date in question, due to both daylight saving time and changes in the standard time observed by a particular government.
See also "Time Zone != Offset" in the timezone tag wiki.
In .NET, the TimeZoneInfo class can manage such changes for you. On Windows, it uses Microsoft time zone identifiers, and on Linux or Mac OSX, it uses IANA time zone identifiers. For example:
// On Windows:
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
DateTime dt = TimeZoneInfo.ConvertTime(DateTime.UtcNow, tz);
// On Linux/OSX:
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("America/New_York");
DateTime dt = TimeZoneInfo.ConvertTime(DateTime.UtcNow, tz);
In both examples, the correct UTC offset (either UTC-5 for EST or UTC-4 for EDT) will be applied.
These could also be written using DateTimeOffset values:
// On Windows:
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
DateTimeOffset dto = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, tz);
// On Linux/OSX:
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("America/New_York");
DateTimeOffset dto = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, tz);
Additionally, if you need to write code that can run on either platform, you can use my TimeZoneConverter library to work with either set of identifiers on any platform.
Why all of you give so complex answers?
Is this wrong?
DateTime.UtcNow.AddHours(-4); //UTC-4

How to use Standard Time Only in TimezoneInfo.ConvertTime C#

I am having a Issue with the C# function of TimeZoneInfo.ConvertTime().
What i need to get is the Standard Time not the DST but i'm only getting DST is there a way to Tell the Function to only get the Result in Standard Time.
My local Timezone is UTC -6:00 Central America Standard Time, so if my time is 12:00 PM the Conversion i'm getting is throwing it at 2 PM Eastern Time but i need it to tell me it's 1:00 PM.
public static DateTime TimetoEst( DateTime timenow)
{
var currentTimeZone = TimeZone.CurrentTimeZone.GetUtcOffset(timenow).ToString();
var estzone = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
var conver = TimeZoneInfo.ConvertTime(timenow, estzone);
return conver;
}
Thanks
A couple of things:
The ID "Eastern Standard Time" represents both EST and EDT, with the appropriate transitions in place. It would more appropriately be called "Eastern Time", but alas this is the identifier and the convention used by Windows time zones.
The Eastern Time zone really does transition in and out of daylight saving time. If you were to always adjust to just Eastern Standard Time (UTC-5), you would be ignoring the reality of timekeeping in that region - that it is in Eastern Daylight Time (UTC-4) for dates in the summer months.
Your code will indeed return EST, but only for date values that are outside of the DST period.
Now, if you still think this is what you want to do - then you can do it without the TimeZoneInfo object at all. Simply adjust the result from the offset that applies to your source value, to the UTC-5 offset that applies to EST.
public static DateTime TimetoEst(DateTime timenow)
{
var dto = new DateTimeOffset(timenow); // will use .Kind to decide the offset
var converted = dto.ToOffset(TimeSpan.FromHours(-5));
return converted.DateTime;
}
This is what you asked, but for the record - I don't think this is the best plan. Besides the issues above - assuming that the input value should be interpreted based on the local time zone is not necessarily a good idea - and unless the input time has a .Kind of DateTimeKind.Utc, it will indeed use the computer's local time zone.
You did label the variable as timenow. If you are just after a DateTime which represents the current time in a fixed offset, then it's much safer just to get it like so:
DateTime dt = DateTimeOffset.UtcNow.ToOffset(TimeSpan.FromHours(-5)).DateTime;
And if you really want the current time in the Eastern Time zone, taking DST into account when appropriate, then:
DateTime dt = TimeZoneInfo.ConvertTimeBySystemTimeZoneId(DateTime.UtcNow,
"Eastern Standard Time");

Is there a way to instantiate a datetime object in a timezone other than local?

I've been racking my brain all afternoon trying to figure this one out. Essentially, the problem itself seems simple. I'm given a date/time that is representative of a date and time in another time zone (not local). I want to convert this value to a UTC value to store in the database. However, all of the methods I find online seem to point to you either starting with UTC or starting with a local time zone. You can convert TO other time zones from these, but you can't start with anything other than those. As a result, it appears that I'll have to do some kind of convoluted offset math to do what I want. Here is an example of the problem:
var dateString = "8/20/2014 6:00:00 AM";
DateTime date1 = DateTime.Parse(dateString,
System.Globalization.CultureInfo.InvariantCulture);
var currentTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");
// Now the server is set to Central Standard Time, so any automated offset calculation that it runs will come from that point of view:
var utcDate = date1.ToUniversalTime; // This is wrong
// Similarly, if I try to reverse-calculate it, it doesn't work either
var convertedDate = TimeZoneInfo.ConvertTime(date1, currentTimeZone);
utcDate = convertedDate.ToUniversalTime; // This is also wrong
In essence, I want to somehow tell the system that the datetime object I'm currently working with is from that time zone other than local, so that I know the conversion will be correct. I know that I'll eventually need to figure Daylight Savings Time in there, but that is a problem for another day.
Would this method be of any use to you ?
The TimeZoneInfo.ConvertTime method converts a time from one time zone
to another.
Alternatively, you could use the ConvertTimeToUtc method to simply convert any date (specifying the source time zone) to UTC.
var dateString = "8/20/2014 6:00:00 AM";
DateTime date1 = DateTime.Parse(dateString,
System.Globalization.CultureInfo.InvariantCulture);
var currentTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");
var utcDate = TimeZoneInfo.ConvertTimeToUtc(date1, currentTimeZone);
The System.DateTime struct only has two bits for storing the "kind" information. That is why you can only have "local" or "universal" or "unknown" (or "magicl local").
Take a look at the System.DateTimeOffset struct. It is like a DateTime, but it also keeps the time zone (offset from (plus or minus) UTC).

Converting a DateTime to Utc given a timezone

I don't want to keep having to change the config everytime there is a daylight savings change. This is what I am currently doing which doesn't work as it uses "Standard" time.
TimeZoneInfo timeZone = TimeZoneInfo.FindSystemTimeZoneById("US Eastern Standard Time")
TimeZoneInfo.ConvertTimeToUtc(dateTime, timeZone); // This doesn't take into account that it's daylight savings...
Is there a one size fits all solution. So I can give it a datetime and a location like "US east coast" and it give me the time in Utc?
I've done it before by storing the timezone id in the database using a mapping table. i.e. A table containing the results of TimeZone.GetSystemTimeZones()
You don't actually need to use TimeZoneInfo.FindSystemTimeZoneById() though: you can do the conversion using one of the overloads of TimeZoneInfo.ConvertTimeBySystemTimeZoneId(). This method has some overloads which take DateTime values, and some that take DateTimeOffset values (which are preferable as they specify an unambiguous point in time).
e.g.
TimeZoneInfo.ConvertTimeBySystemTimeZoneId(DateTime.Now, "New Zealand Standard Time", "UTC")
The real benefit of using the system time zone id rather than an offset stored in the database is that daylight savings time is automatically handled for you by TimeZoneInfo.ConvertTimeBySystemTimeZoneId.
This msdn also might prove helpful to you>
http://msdn.microsoft.com/en-us/library/bb382058.aspx
You Can Pass DateTime and TimeZone of the Location and Convert the provided DateTime to UTC
Check this Example Here
string DisplayName = "custom standard name here";//custom Standard Name to display eg: Kathmandu
string StandardName = "custom standard name here"; // custom Standard Name eg: Asia/Kathamandu, Nepal
string YourDate="27-03-2019 20:24:56"; // this DateTime doesn't contain any timeZone
TimeSpan Offset = new TimeSpan(+5, 30, 00);// your TimeZone offset eg: timeZone of Nepal is +5:45
TimeZoneInfo TimeZone = TimeZoneInfo.CreateCustomTimeZone(StandardName, Offset, DisplayName, StandardName);
var RawDateTime = DateTime.SpecifyKind(DateTime.Parse(YourDate), DateTimeKind.Unspecified);// I all it RawDateTime Since it doesn't contain any TimeSpan
DateTime UTCDateTime = TimeZoneInfo.ConvertTimeToUtc(RawDateTime, TimeZone);
Console.WriteLine(UTCDateTime);

Categories