DateTime doubts in .NET for all countries

Question

Hi all I have some doubt for datetime .

For the system.DateTime.Now is return current local date .

The below code is helps to get current indian datetime

Dim IndianTimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("India Standard Time")
Dim IndianDateTime = TimeZoneInfo.ConvertTime(USDateTime, IndianTimeZoneInfo)

But at this time The US and UK , etc country have different datetimes . How can i manage it in simple code ?

The main doubt for the above code is got indian time only , But if we want to US or other country time , We need to separate codes for different countries (if yes, Then we write lot of codes , It's good ?)? or any other idea's there ?

Please advice me . Thanks !

Edit:

simple my question is how to store current date time for different different countries?

Answer 1

@RameshRajendran here is an article and some code from the article that I'm sure will not complete your project. But hopefully it with help you see it from a different perspective. As @varocarbas pointed out it will serve you well to create a table to store your final compiled info.

Link to article: http://msdn.microsoft.com/en-us/library/vstudio/bb397781(v=vs.110).aspx

You can use the SupportsDaylightSavingTime property to see if there are rules for the timezone.

You can also use the Object Browser in Visual Studio to see the members of the System.TimeZoneInfo.

I tested this with the following in the index ActionResult of the controller and the html helper in the index view. Again, This is just to help you see your way past the 'Lots of work' block you seem to be uncomfortable with.

I've written this code using c#, but I'm sure you'll have no trouble creating the equivilant in VB.

[ Controller ]

// Sample code from the article.
// Note: the collection only contains full hour offsets (i.e. New Delhi is in a half hour zone)
ReadOnlyCollection<TimeZoneInfo> tzCollection;
tzCollection = TimeZoneInfo.GetSystemTimeZones();

foreach (TimeZoneInfo timeZone in tzCollection)
    {
        Console.WriteLine("   {0}: {1}", timeZone.Id, timeZone.DisplayName);
    }

// My modified version of its use.
// this code will create a dropdownlist with all the timezones available on my machine.
var theTimesInfo = new List<TimeZoneInfo>(tzCollection);
var theZones = new SelectList(theTimesInfo, "Id", "DisplayName", 1);

ViewData["theZones"] = theZones;

string myLocalZone = "Eastern Standard Time";
TimeZoneInfo myLocalDateTime = TimeZoneInfo.FindSystemTimeZoneById(myLocalZone);

string theZoneSelected = Request.QueryString.Get("theZones");
if (theZoneSelected == string.Empty || theZoneSelected == null)
{
    theZoneSelected = myLocalZone;
}

TimeZoneInfo selectedTimeZone = TimeZoneInfo.FindSystemTimeZoneById(theZoneSelected);
DateTime CurrentTimeZoneDateAndTime = TimeZoneInfo.ConvertTime((DateTime.SpecifyKind(DateTime.Now, DateTimeKind.Unspecified)), myLocalDateTime, selectedTimeZone);

ViewBag.CurrentTimeZoneSelected = selectedTimeZone.DisplayName.ToString();
ViewBag.CurrentDateTimeSelected = CurrentTimeZoneDateAndTime.ToString();

[updated] edited the view code to show the values returned.

[ View ]

<p>
    The Select TimeZone is: @ViewBag.CurrentTimeZoneSelected<br />
    The current Date and Time for the Selected TimeZone is: @ViewBag.CurrentDateTimeSelected
</p>

<form>
    @Html.DropDownList("theZones", ViewData["theZones"] as SelectList)
    <input type="submit" name="submit" value="Select This Time Zone" />
</form>

You can use the foreach loop to iterate through the collection and add it to your db table. Then if you need to, you can add individual entries to the table, or adjust the +- as needed.

Answer 2

You can save the time as the UTC time, using datetime.UtcNow.

You can convert to another country's time zone using TimeZoneInfo.ConvertTime, as you did in your example, converting either Now or UtcNow dates.

The problem seems to be how to get all the timezone info. You can do that with GetSystemTimeZones. The official timezone name is in timeZoneInfo.id.

Dim zones As System.Collections.ObjectModel.ReadOnlyCollection(Of TimeZoneInfo) = TimeZoneInfo.GetSystemTimeZones()
Dim hSpan As TimeSpan

For Each zone As TimeZoneInfo In zones
  If InStr(LCase(zone.Id), "greenland") > 0 Then
    ' zone has the timezoneinfo for greenland.
    ' the following line assigns hSpan the difference between Greenland time and UTC.
    ' Be careful -- there may be more than one Greenland time. A combo box would be safer.
    hSpan = zone.GetUtcOffset(Now)
    exit for
  End If
Next zone

You can get the current time zone offset of the client browser in Javascript, something like this:

function GetClientUTC()
{
var now = new Date();
var offset = now.getTimezoneOffset();
}