Time Zone Class

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• Download demo project - 23.4 KB

Introduction

This is yet another time zone class that gives you full access and functionality for different time zones. As we all know, .NET's (up to Framework 2) Time Zone class is not of much use since it only gives us objects that are associated with the current time zone. Therefore, I decided to create a time zone class called TimeZoneInfo that can give us information and methods for the other time zones.

The TimeZoneInfo class does pure .NET implementation and uses only one API method to set the current system computer's TimeZone. This means 99% managed code compared to some other time zone implementations.

Background

I have seen many time zone classes, but almost all of them were lacking some features or the functions were implemented incorrectly. Time zone class may seem to be an easy task at first, but believe me, it is kind of tricky. The TimeZoneInfo class is based on the windows registry information under the key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\Time Zones, so it is critical that the registry includes the latest updates from Microsoft.
The class provides all the information and the functionality for the time zones. For example, it provides Daylight Saving Time dates for the time zone, Current UtcOffset, Current Time, Current System Time Zone etc.

Used API Functions

Name	Purpose
SetTimeZoneInformation	To set the current system time zone

Properties

Name	Description
DisplayName	Gets the display name of the time zone
DaylightName	Gets the daylight saving name of the time zone
StandardName	Gets the standard name of the time zone
CurrentTime	Gets the current date and time of the time zone
CurrentUtcOffset	Gets the current UTC (Coordinated Universal Time) offset of the time zone
CurrentTimeZone	Gets or sets the current time zone for this computer system
StandardUtcOffset	Gets the standard UTC (Coordinated Universal Time) offset of the time zone
Id	Gets the id of the time zone

Methods

Name	Description	Parameter	Return Value
GetTimeZones	Gets an array of all time zones on the system	None	Array of TimeZoneInfo
FromStandardName	Gets a TimeZoneInfo.Object from standard name	Standard Name (string)	TimeZoneInfo
FromId	Gets a TimeZoneInfo.Object from Id	Id (string)	TimeZoneInfo
GetDaylightChanges	Returns the daylight saving time for a particular year	Year (Integer)	DaylightTime
IsDaylightSavingTime	Returns a value indicating whether this time zone is within a daylight saving time period	None	True/False (Boolean)
Refresh	Refreshes the information of the time zone object	None	None
Sort	Sorts the elements in a list(Of TimeZoneInfo) object/TimeZoneInfo array based on standard UTC offset or display name	tzInfos (List(Of TimeZoneInfo)/TimeZoneInfo array	None
ToString	Returns a System.String that represents the current TimeZoneInfo object	none	Display Name (String)
Equals	Determines whether the specified System.Object is equal to the current System.Object	obj (Object)	True/False (Boolean)

Using The Code

For more examples, check the demo project.

'Get all the time zones on the system and show them in a ListBox control

Me.ListBox1.DataSource = TimeZoneInfo.GetTimeZones

Dim tzInfo As TimeZoneInfo 
'Create new instance of a TimeZoneInfo for a specific time zone 

tzInfo = New TimeZoneInfo("Pacific Standard Time") 
'Or tzInfo = TimeZoneInfo.FromStandardName("Pacific Standard Time") 

'Get the current UtcOffset of the time zone 

Dim utcOffset As TimeSpan = tzInfo.CurrentUtcOffset 
'Get the current time of the time zone 

Dim time As DateTime = tzInfo.CurrentTime 
'Get a value specifying if it is a daylight saving time 

'currently for the time zone 

Dim isDaylight As Boolean = tzInfo.IsDaylightSavingTime 
'Get daylight changes for the year 2007 of the time zone 

Dim dStart, dEnd As DateTime 
Dim dt As System.Globalization.DaylightTime 
dt = tzInfo.GetDaylightChanges(2007) 
dStart = dt.Start 
dEnd = dt.End 
'And much more 

'... 

'... 

System Requirements

• Windows NT/2000/XP (tested only on XP)
• Framework 2.0

TimeZoneInfo Information

• Author name: Arman Ghazanchyan
• External link to TimeZoneInfo class

History

• 12 September, 2007 -- Original version posted
• 17 September, 2007 -- (Some internal minor changes to optimize the Sort functionality)