DateTime.ToUniversalTime Method
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Converts the value of the current DateTime object to Coordinated Universal Time (UTC).
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Function ToUniversalTime As DateTime
public DateTime ToUniversalTime()
Return Value
Type: System.DateTime
An object whose Kind property is Utc, and whose value is one of the following: the UTC equivalent of the current DateTime value, or DateTime.MaxValue if the converted value is too large to be represented by a DateTime object, or DateTime.MinValue if the converted value is too small to be represented by a DateTime object.
Remarks
The Coordinated Universal Time (UTC) is equal to the local time minus the UTC offset. The conversion also takes into account the daylight saving time rule that applies to the time represented by the current DateTime object.
.gif "Important note") Important Note: |
|---|
The ToUniversalTime method recognizes only the current adjustment rule when converting from local time to UTC. As a result, conversions for periods before the current adjustment rule came into effect may not accurately reflect the difference between local time and UTC. |
The value returned by the ToUniversalTime method is determined by the Kind property of the current DateTime object. The following table describes the possible results.
Kind |
Results |
|---|---|
No conversion is performed. |
|
The current DateTime object is converted to UTC. |
|
The current DateTime object is assumed to be a local time, and the conversion is performed as if Kind were Local. |
.gif "Note") Note: |
|---|
The ToUniversalTime method converts a DateTime value from local time to UTC. To convert a time whose offset from UTC is known, use the ToUniversalTime method. |
If the date and time instance value is an ambiguous time, this method assumes that it is a standard time. (An ambiguous time is one that can map either to a standard time or to a daylight saving time in the local time zone) If the date and time instance value is an invalid time, this method simply subtracts the local time from the local time zone's UTC offset to return UTC. (An invalid time is one that does not exist because of the application of daylight saving time adjustment rules.)
Notes to Callers
The ToUniversalTime method is sometimes used to convert a local time to UTC, and subsequently to restore it by calling the ToLocalTime method. However, if the original time represents an invalid time in the local time zone, the two local time values will not be equal. For additional information and an example, see the ToLocalTime method.
Examples
The following example demonstrates the ToUniversalTime method.
outputBlock.Text += "Enter a date and time." + vbCrLf
Dim strDateTime As String
strDateTime = System.Console.ReadLine()
Dim localDateTime As System.DateTime
Try
localDateTime = System.DateTime.Parse(strDateTime)
Catch exp As System.FormatException
outputBlock.Text += "Invalid format." + vbCrLf
End Try
Dim univDateTime As System.DateTime
univDateTime = localDateTime.ToUniversalTime()
outputBlock.Text += String.Format("{0} local time is {1} universal time.", _
localDateTime, _
univDateTime) + vbCrLf
outputBlock.Text += String.Format("Enter a date and time in universal time.") + vbCrLf
strDateTime = System.Console.ReadLine()
Try
univDateTime = System.DateTime.Parse(strDateTime)
Catch exp As System.FormatException
outputBlock.Text += "Invalid format." + vbCrLf
End Try
localDateTime = univDateTime.ToLocalTime()
outputBlock.Text += String.Format("{0} universal time is {1} local time.", _
univDateTime, _
localDateTime) + vbCrLf
outputBlock.Text += "Enter a date and time." + "\n";
string strDateTime = System.Console.ReadLine();
System.DateTime localDateTime;
try
{
localDateTime = System.DateTime.Parse(strDateTime);
}
catch (System.FormatException)
{
outputBlock.Text += "Invalid format." + "\n";
return;
}
System.DateTime univDateTime = localDateTime.ToUniversalTime();
outputBlock.Text += String.Format("{0} local time is {1} universal time.",
localDateTime,
univDateTime) + "\n";
outputBlock.Text += "Enter a date and time in universal time." + "\n";
strDateTime = System.Console.ReadLine();
try
{
univDateTime = System.DateTime.Parse(strDateTime);
}
catch (System.FormatException)
{
outputBlock.Text += "Invalid format." + "\n";
return;
}
localDateTime = univDateTime.ToLocalTime();
outputBlock.Text += String.Format("{0} universal time is {1} local time.",
univDateTime,
localDateTime) + "\n";
The following example uses the SpecifyKind method to demonstrate how the Kind property influences the ToLocalTime and ToUniversalTime conversion methods.
' This code example demonstrates the DateTime Kind, Now, and
' UtcNow properties, and the SpecifyKind(), ToLocalTime(),
' and ToUniversalTime() methods.
Class Example
Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
' Get the date and time for the current moment, adjusted
' to the local time zone.
Dim saveNow As DateTime = DateTime.Now
' Get the date and time for the current moment expressed
' as coordinated universal time (UTC).
Dim saveUtcNow As DateTime = DateTime.UtcNow
Dim myDt As DateTime
' Display the value and Kind property of the current moment
' expressed as UTC and local time.
DisplayNow(outputBlock, "UtcNow: ..........", saveUtcNow)
DisplayNow(outputBlock, "Now: .............", saveNow)
outputBlock.Text &= vbCrLf
' Change the Kind property of the current moment to
' DateTimeKind.Utc and display the result.
myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Utc)
Display(outputBlock, "Utc: .............", myDt)
' Change the Kind property of the current moment to
' DateTimeKind.Local and display the result.
myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Local)
Display(outputBlock, "Local: ...........", myDt)
' Change the Kind property of the current moment to
' DateTimeKind.Unspecified and display the result.
myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Unspecified)
Display(outputBlock, "Unspecified: .....", myDt)
End Sub 'Main
' Display the value and Kind property of a DateTime structure, the
' DateTime structure converted to local time, and the DateTime
' structure converted to universal time.
Public Shared datePatt As String = "M/d/yyyy hh:mm:ss tt"
Public Shared Sub Display(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal title As String, ByVal inputDt As DateTime)
Dim dispDt As DateTime = inputDt
Dim dtString As String
' Display the original DateTime.
dtString = dispDt.ToString(datePatt)
outputBlock.Text += String.Format("{0} {1}, Kind = {2}", title, dtString, dispDt.Kind) & vbCrLf
' Convert inputDt to local time and display the result.
' If inputDt.Kind is DateTimeKind.Utc, the conversion is performed.
' If inputDt.Kind is DateTimeKind.Local, the conversion is not performed.
' If inputDt.Kind is DateTimeKind.Unspecified, the conversion is
' performed as if inputDt was universal time.
dispDt = inputDt.ToLocalTime()
dtString = dispDt.ToString(datePatt)
outputBlock.Text += String.Format(" ToLocalTime: {0}, Kind = {1}", dtString, dispDt.Kind) & vbCrLf
' Convert inputDt to universal time and display the result.
' If inputDt.Kind is DateTimeKind.Utc, the conversion is not performed.
' If inputDt.Kind is DateTimeKind.Local, the conversion is performed.
' If inputDt.Kind is DateTimeKind.Unspecified, the conversion is
' performed as if inputDt was local time.
dispDt = inputDt.ToUniversalTime()
dtString = dispDt.ToString(datePatt)
outputBlock.Text += String.Format(" ToUniversalTime: {0}, Kind = {1}", dtString, dispDt.Kind) & vbCrLf
outputBlock.Text &= vbCrLf
End Sub 'Display
' Display the value and Kind property for DateTime.Now and DateTime.UtcNow.
Public Shared Sub DisplayNow(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal title As String, ByVal inputDt As DateTime)
Dim dtString As String = inputDt.ToString(datePatt)
outputBlock.Text += String.Format("{0} {1}, Kind = {2}", title, dtString, inputDt.Kind) & vbCrLf
End Sub 'DisplayNow
End Class 'Sample
'
'This code example produces the following results:
'
'UtcNow: .......... 5/6/2005 09:34:42 PM, Kind = Utc
'Now: ............. 5/6/2005 02:34:42 PM, Kind = Local
'
'Utc: ............. 5/6/2005 02:34:42 PM, Kind = Utc
' ToLocalTime: 5/6/2005 07:34:42 AM, Kind = Local
' ToUniversalTime: 5/6/2005 02:34:42 PM, Kind = Utc
'
'Local: ........... 5/6/2005 02:34:42 PM, Kind = Local
' ToLocalTime: 5/6/2005 02:34:42 PM, Kind = Local
' ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc
'
'Unspecified: ..... 5/6/2005 02:34:42 PM, Kind = Unspecified
' ToLocalTime: 5/6/2005 07:34:42 AM, Kind = Local
' ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc
'
// This code example demonstrates the DateTime Kind, Now, and
// UtcNow properties, and the SpecifyKind(), ToLocalTime(),
// and ToUniversalTime() methods.
using System;
class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
// Get the date and time for the current moment, adjusted
// to the local time zone.
DateTime saveNow = DateTime.Now;
// Get the date and time for the current moment expressed
// as coordinated universal time (UTC).
DateTime saveUtcNow = DateTime.UtcNow;
DateTime myDt;
// Display the value and Kind property of the current moment
// expressed as UTC and local time.
DisplayNow(outputBlock, "UtcNow: ..........", saveUtcNow);
DisplayNow(outputBlock, "Now: .............", saveNow);
outputBlock.Text += "\n";
// Change the Kind property of the current moment to
// DateTimeKind.Utc and display the result.
myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Utc);
Display(outputBlock, "Utc: .............", myDt);
// Change the Kind property of the current moment to
// DateTimeKind.Local and display the result.
myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Local);
Display(outputBlock, "Local: ...........", myDt);
// Change the Kind property of the current moment to
// DateTimeKind.Unspecified and display the result.
myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Unspecified);
Display(outputBlock, "Unspecified: .....", myDt);
}
// Display the value and Kind property of a DateTime structure, the
// DateTime structure converted to local time, and the DateTime
// structure converted to universal time.
public static string datePatt = @"M/d/yyyy hh:mm:ss tt";
public static void Display(System.Windows.Controls.TextBlock outputBlock, string title, DateTime inputDt)
{
DateTime dispDt = inputDt;
string dtString;
// Display the original DateTime.
dtString = dispDt.ToString(datePatt);
outputBlock.Text += String.Format("{0} {1}, Kind = {2}",
title, dtString, dispDt.Kind) + "\n";
// Convert inputDt to local time and display the result.
// If inputDt.Kind is DateTimeKind.Utc, the conversion is performed.
// If inputDt.Kind is DateTimeKind.Local, the conversion is not performed.
// If inputDt.Kind is DateTimeKind.Unspecified, the conversion is
// performed as if inputDt was universal time.
dispDt = inputDt.ToLocalTime();
dtString = dispDt.ToString(datePatt);
outputBlock.Text += String.Format(" ToLocalTime: {0}, Kind = {1}",
dtString, dispDt.Kind) + "\n";
// Convert inputDt to universal time and display the result.
// If inputDt.Kind is DateTimeKind.Utc, the conversion is not performed.
// If inputDt.Kind is DateTimeKind.Local, the conversion is performed.
// If inputDt.Kind is DateTimeKind.Unspecified, the conversion is
// performed as if inputDt was local time.
dispDt = inputDt.ToUniversalTime();
dtString = dispDt.ToString(datePatt);
outputBlock.Text += String.Format(" ToUniversalTime: {0}, Kind = {1}",
dtString, dispDt.Kind) + "\n";
outputBlock.Text += "\n";
}
// Display the value and Kind property for DateTime.Now and DateTime.UtcNow.
public static void DisplayNow(System.Windows.Controls.TextBlock outputBlock, string title, DateTime inputDt)
{
string dtString = inputDt.ToString(datePatt);
outputBlock.Text += String.Format("{0} {1}, Kind = {2}",
title, dtString, inputDt.Kind) + "\n";
}
}
/*
This code example produces the following results:
UtcNow: .......... 5/6/2005 09:34:42 PM, Kind = Utc
Now: ............. 5/6/2005 02:34:42 PM, Kind = Local
Utc: ............. 5/6/2005 02:34:42 PM, Kind = Utc
ToLocalTime: 5/6/2005 07:34:42 AM, Kind = Local
ToUniversalTime: 5/6/2005 02:34:42 PM, Kind = Utc
Local: ........... 5/6/2005 02:34:42 PM, Kind = Local
ToLocalTime: 5/6/2005 02:34:42 PM, Kind = Local
ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc
Unspecified: ..... 5/6/2005 02:34:42 PM, Kind = Unspecified
ToLocalTime: 5/6/2005 07:34:42 AM, Kind = Local
ToUniversalTime: 5/6/2005 09:34:42 PM, Kind = Utc
*/
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.