Partager via

  • Article

DateTime.ToLocalTime Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Converts the value of the current DateTime object to local time.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public Function ToLocalTime As DateTime

public DateTime ToLocalTime()

Return Value

Type: System.DateTime
An object whose Kind property is Local, and whose value is one of the following: the local time 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 as a DateTime object.

Remarks

The local time is equal to the Coordinated Universal Time (UTC) time plus 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.

Important noteImportant Note:

The ToLocalTime method recognizes only the current adjustment rule when converting from UTC to local time. As a result, conversions for periods before the current adjustment rule came into effect may not accurately reflect the difference between UTC and local time.

The value returned by the ToLocalTime method is determined by the Kind property of the current DateTime object. The following table describes the possible results.

Kind property value

Result

Utc

This instance of DateTime is converted to local time.

Local

No conversion is performed.

Unspecified

This instance of DateTime is assumed to be a UTC time, and the conversion is performed as if Kind were Utc.

The value returned by the conversion is a DateTime whose Kind property always returns Local. Consequently, a valid result is returned even if ToLocalTime is applied repeatedly to the same DateTime.

Notes to Callers

You can use the ToLocalTime method to restore a local date and time value that was converted to UTC by the ToUniversalTime or FromFileTimeUtc method. However, if the original time represents an invalid time in the local time zone, it will not match the restored value. When the ToLocalTime method converts a time from UTC to the local time zone, it also adjusts the time so that is valid in the local time zone.

For example, the transition from standard time to daylight saving time occurs in the U.S. Pacific Standard Time zone on March 14, 2010, at 2:00 A.M., when the time advances by one hour, to 3:00 AM. This hour interval is an invalid time, that is, a time interval that does not exist in this time zone. The following example shows that when a time that falls within this range is converted to UTC by the ToUniversalTime method and is then restored by the ToLocalTime method, the original value is adjusted to become a valid time. You can determine whether a particular date and time value may be subject to modification by passing it to the TimeZoneInfo.IsInvalidTime method, as the example illustrates.

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim date1 As New Date(2010, 3, 14, 2, 30, 0, DateTimeKind.Local)
      outputBlock.Text += String.Format("Invalid time: {0}", _
                        TimeZoneInfo.Local.IsInvalidTime(date1)) & vbCrLf
      Dim utcDate1 As Date = date1.ToUniversalTime()
      Dim date2 As Date = utcDate1.ToLocalTime()
      outputBlock.Text += String.Format("{0} --> {1}", date1, date2) & vbCrLf
   End Sub
End Module
' The example displays the following output:
'       Invalid time: True
'       3/14/2010 2:30:00 AM --> 3/14/2010 3:30:00 AM

using System;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      DateTime date1 = new DateTime(2010, 3, 14, 2, 30, 0, DateTimeKind.Local);
      outputBlock.Text += String.Format("Invalid time: {0}",
                        TimeZoneInfo.Local.IsInvalidTime(date1)) + "\n";
      DateTime utcDate1 = date1.ToUniversalTime();
      DateTime date2 = utcDate1.ToLocalTime();
      outputBlock.Text += String.Format("{0} --> {1}", date1, date2) + "\n";
   }
}
// The example displays the following output:
//       Invalid time: True
//       3/14/2010 2:30:00 AM --> 3/14/2010 3:30:00 AM

Examples

The following example demonstrates the ToLocalTime 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.