DateTime.ToUniversalTime DateTime.ToUniversalTime DateTime.ToUniversalTime DateTime.ToUniversalTime Method

Definizione

Converte il valore dell'oggetto DateTime corrente nell'ora UTC (Coordinated Universal Time).Converts the value of the current DateTime object to Coordinated Universal Time (UTC).

public:
 DateTime ToUniversalTime();
public DateTime ToUniversalTime ();
member this.ToUniversalTime : unit -> DateTime
Public Function ToUniversalTime () As DateTime

Restituisce

Oggetto la cui proprietà Kind è Utc e il cui valore è l'ora UTC equivalente al valore dell'oggetto DateTime corrente oppure MaxValue se il valore convertito è troppo grande per essere rappresentato da un oggetto DateTime oppure MinValue se il valore convertito è troppo piccolo per essere rappresentato da un oggetto DateTime.An object whose Kind property is Utc, and whose value is the UTC equivalent to the value of the current DateTime object, or MaxValue if the converted value is too large to be represented by a DateTime object, or MinValue if the converted value is too small to be represented by a DateTime object.

Esempi

Nell'esempio seguente viene illustrato ToUniversalTime il metodo.The following example demonstrates the ToUniversalTime method.

using namespace System;

void main()
{
   Console::WriteLine("Enter a date and time.");
   String^ strDateTime = Console::ReadLine();

   DateTime localDateTime, univDateTime;
   try
   {
      localDateTime = DateTime::Parse(strDateTime);
      univDateTime = localDateTime.ToUniversalTime();
    
      Console::WriteLine("{0} local time is {1} universal time.",
                         localDateTime, univDateTime );
   }
   catch (FormatException^) 
   {
      Console::WriteLine("Invalid format.");
      return;
   }

   Console::WriteLine("Enter a date and time in universal time.");
   strDateTime = Console::ReadLine();

   try
   {
      univDateTime = DateTime::Parse(strDateTime);
      localDateTime = univDateTime.ToLocalTime();
  
      Console::WriteLine("{0} universal time is {1} local time.",
                         univDateTime, localDateTime );
   }
   catch (FormatException^) 
   {
      Console::WriteLine("Invalid format.");
      return;
   }
}
// The example displays output like the following when run on a 
// computer whose culture is en-US in the Pacific Standard Time zone:
//     Enter a date and time.
//     12/10/2015 6:18 AM
//     12/10/2015 6:18:00 AM local time is 12/10/2015 2:18:00 PM universal time.
//     Enter a date and time in universal time.
//     12/20/2015 6:42:00
//     12/20/2015 6:42:00 AM universal time is 12/19/2015 10:42:00 PM local time.
using System;

class Example
{
	static void Main()
	{
		DateTime localDateTime, univDateTime;
		
		Console.WriteLine("Enter a date and time.");
		string strDateTime = Console.ReadLine();

		try {
			localDateTime = DateTime.Parse(strDateTime);
    		univDateTime = localDateTime.ToUniversalTime();
    
    		Console.WriteLine("{0} local time is {1} universal time.",
   								localDateTime,
    								univDateTime); 
		}
		catch (FormatException) {
			Console.WriteLine("Invalid format.");
			return;
		}

		Console.WriteLine("Enter a date and time in universal time.");
		strDateTime = Console.ReadLine();

		try {
			univDateTime = DateTime.Parse(strDateTime);
    		localDateTime = univDateTime.ToLocalTime();
    
    		Console.WriteLine("{0} universal time is {1} local time.",
    								 univDateTime,
    								 localDateTime); 
		}
		catch (FormatException) {
			Console.WriteLine("Invalid format.");
			return;
		}

	}
}
// The example displays output like the following when run on a 
// computer whose culture is en-US in the Pacific Standard Time zone:
//     Enter a date and time.
//     12/10/2015 6:18 AM
//     12/10/2015 6:18:00 AM local time is 12/10/2015 2:18:00 PM universal time.
//     Enter a date and time in universal time.
//     12/20/2015 6:42:00
//     12/20/2015 6:42:00 AM universal time is 12/19/2015 10:42:00 PM local time.
Module Example
    Sub Main()
      Dim localDateTime, univDateTime As DateTime
      
      Console.WriteLine("Enter a date and time.")
      Dim strDateTime As String = Console.ReadLine()
      Try
         localDateTime = DateTime.Parse(strDateTime)
         univDateTime = localDateTime.ToUniversalTime()
         Console.WriteLine("{0} local time is {1} universal time.", 
                           localDateTime, univDateTime)
      Catch exp As FormatException
         Console.WriteLine("Invalid format.")
      End Try

      Console.WriteLine("Enter a date and time in universal time.")
      strDateTime = Console.ReadLine()
      Try
         univDateTime = DateTime.Parse(strDateTime)
         localDateTime = univDateTime.ToLocalTime()
  
         Console.WriteLine("{0} universal time is {1} local time.", _
                           univDateTime, localDateTime)
      Catch exp As FormatException
         Console.WriteLine("Invalid format.")
      End Try
    End Sub
End Module
' The example displays output like the following when run on a 
' computer whose culture is en-US in the Pacific Standard Time zone:
'     Enter a date and time.
'     12/10/2015 6:18 AM
'     12/10/2015 6:18:00 AM local time is 12/10/2015 2:18:00 PM universal time.
'     Enter a date and time in universal time.
'     12/20/2015 6:42:00
'     12/20/2015 6:42:00 AM universal time is 12/19/2015 10:42:00 PM local time.

Nell'esempio seguente viene usato SpecifyKind il metodo per illustrare Kind il modo in cui ToUniversalTime la proprietà influenza i ToLocalTime metodi di conversione e.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.

using System;

class Sample 
{
    public static void Main() 
    {
// 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("UtcNow: ..........", saveUtcNow);
    DisplayNow("Now: .............", saveNow);
    Console.WriteLine();

// Change the Kind property of the current moment to 
// DateTimeKind.Utc and display the result.

    myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Utc);
    Display("Utc: .............", myDt);

// Change the Kind property of the current moment to 
// DateTimeKind.Local and display the result.

    myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Local);
    Display("Local: ...........", myDt);

// Change the Kind property of the current moment to 
// DateTimeKind.Unspecified and display the result.

    myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Unspecified);
    Display("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(string title, DateTime inputDt)
    {
    DateTime dispDt = inputDt;
    string dtString;

// Display the original DateTime.

    dtString = dispDt.ToString(datePatt);
    Console.WriteLine("{0} {1}, Kind = {2}", 
                      title, dtString, dispDt.Kind);

// 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);
    Console.WriteLine("  ToLocalTime:     {0}, Kind = {1}", 
                      dtString, dispDt.Kind);

// 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);
    Console.WriteLine("  ToUniversalTime: {0}, Kind = {1}", 
                      dtString, dispDt.Kind);
    Console.WriteLine();
    }

// Display the value and Kind property for DateTime.Now and DateTime.UtcNow.

    public static void DisplayNow(string title, DateTime inputDt)
    {
    string dtString = inputDt.ToString(datePatt);
    Console.WriteLine("{0} {1}, Kind = {2}", 
                      title, dtString, inputDt.Kind);
    }
}

/*
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.
Imports System

Class Sample
    Public Shared Sub Main() 
        ' 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("UtcNow: ..........", saveUtcNow)
        DisplayNow("Now: .............", saveNow)
        Console.WriteLine()
        
        ' Change the Kind property of the current moment to 
        ' DateTimeKind.Utc and display the result.
        myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Utc)
        Display("Utc: .............", myDt)
        
        ' Change the Kind property of the current moment to 
        ' DateTimeKind.Local and display the result.
        myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Local)
        Display("Local: ...........", myDt)
        
        ' Change the Kind property of the current moment to 
        ' DateTimeKind.Unspecified and display the result.
        myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Unspecified)
        Display("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 title As String, ByVal inputDt As DateTime) 
        Dim dispDt As DateTime = inputDt
        Dim dtString As String
        
        ' Display the original DateTime.
        dtString = dispDt.ToString(datePatt)
        Console.WriteLine("{0} {1}, Kind = {2}", title, dtString, dispDt.Kind)
        
        ' 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)
        Console.WriteLine("  ToLocalTime:     {0}, Kind = {1}", dtString, dispDt.Kind)
        
        ' 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)
        Console.WriteLine("  ToUniversalTime: {0}, Kind = {1}", dtString, dispDt.Kind)
        Console.WriteLine()
    End Sub 'Display
    
    
    ' Display the value and Kind property for DateTime.Now and DateTime.UtcNow.

    Public Shared Sub DisplayNow(ByVal title As String, ByVal inputDt As DateTime) 
        Dim dtString As String = inputDt.ToString(datePatt)
        Console.WriteLine("{0} {1}, Kind = {2}", title, dtString, inputDt.Kind)
    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
'

Commenti

L'ora UTC (Coordinated Universal Time) è uguale all'ora locale meno l'offset UTC.The Coordinated Universal Time (UTC) is equal to the local time minus the UTC offset. Per ulteriori informazioni sull'offset UTC, vedere TimeZone.GetUtcOffset.For more information about the UTC offset, see TimeZone.GetUtcOffset. La conversione prende in considerazione anche la regola dell'ora legale che si applica all'ora rappresentata dall'oggetto DateTime corrente.The conversion also takes into account the daylight saving time rule that applies to the time represented by the current DateTime object.

Importante

Nei Windows XPWindows XP sistemi, il ToUniversalTime metodo riconosce solo la regola di rettifica corrente quando si esegue la conversione dall'ora locale in ora UTC.On Windows XPWindows XP systems, the ToUniversalTime method recognizes only the current adjustment rule when converting from local time to UTC. Di conseguenza, le conversioni per i punti prima della regola di rettifica corrente sono state attivate potrebbe non riflettere accuratamente la differenza tra l'ora locale e l'ora 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.

A partire dalla versione .NET Framework 2,0, il valore restituito dal ToUniversalTime metodo è determinato Kind dalla proprietà dell'oggetto corrente DateTime .Starting with the .NET Framework version 2.0, the value returned by the ToUniversalTime method is determined by the Kind property of the current DateTime object. Nella tabella seguente vengono descritti i possibili risultati.The following table describes the possible results.

TipoKind RisultatiResults
Utc Non viene eseguita alcuna conversione.No conversion is performed.
Local L'oggetto DateTime corrente viene convertito in ora UTC.The current DateTime object is converted to UTC.
Unspecified Si presuppone DateTime che l'oggetto corrente sia un'ora locale e che la conversione venga eseguita come se Kind fosse Local.The current DateTime object is assumed to be a local time, and the conversion is performed as if Kind were Local.

Nota

Il ToUniversalTime metodo converte un DateTime valore dall'ora locale in ora UTC.The ToUniversalTime method converts a DateTime value from local time to UTC. Per convertire l'ora in un fuso orario non locale in UTC, utilizzare il TimeZoneInfo.ConvertTimeToUtc(DateTime, TimeZoneInfo) metodo.To convert the time in a non-local time zone to UTC, use the TimeZoneInfo.ConvertTimeToUtc(DateTime, TimeZoneInfo) method. Per convertire un'ora il cui offset rispetto all'ora UTC è noto ToUniversalTime , utilizzare il metodo.To convert a time whose offset from UTC is known, use the ToUniversalTime method.

Se il valore dell'istanza di data e ora è un'ora ambigua, questo metodo presuppone che si tratta di un'ora standard.If the date and time instance value is an ambiguous time, this method assumes that it is a standard time. (Un'ora ambigua può essere mappata a un'ora solare o a un'ora legale nel fuso orario locale) Se il valore dell'istanza di data e ora non è valido, questo metodo sottrae l'ora locale dall'offset UTC del fuso orario locale per restituire l'ora UTC.(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. (Un'ora non valida è un'ora che non esiste a causa dell'applicazione delle regole di regolazione dell'ora legale).(An invalid time is one that does not exist because of the application of daylight saving time adjustment rules.)

Note per i chiamanti

Il ToUniversalTime() metodo viene talvolta utilizzato per convertire un'ora locale in ora UTC.The ToUniversalTime() method is sometimes used to convert a local time to UTC. Il ToLocalTime() metodo viene quindi chiamato per ripristinare l'ora locale originale.The ToLocalTime() method is then called to restore the original local time. Tuttavia, se l'ora originale rappresenta un'ora non valida nel fuso orario locale, i due valori di ora locale non saranno uguali.However, if the original time represents an invalid time in the local time zone, the two local time values will not be equal. Per ulteriori informazioni e un esempio, vedere il ToLocalTime() metodo.For additional information and an example, see the ToLocalTime() method.

Nei Windows XPWindows XP sistemi, il ToUniversalTime() metodo riconosce solo la regola di rettifica corrente per il fuso orario locale, che si applica a tutte le date, incluse le date di livello inferiore, ovvero le date precedenti alla data di inizio della regolazione corrente regola).On Windows XPWindows XP systems, the ToUniversalTime() method recognizes only the current adjustment rule for the local time zone, which it applies to all dates, including down-level dates (that is, dates that are earlier than the starting date of the current adjustment rule). Le applicazioni in Windows XPWindows XP esecuzione in che richiedono calcoli di data e ora locali con precisione storica devono aggirare questo comportamento FindSystemTimeZoneById(String) usando il metodo per TimeZoneInfo recuperare un oggetto che corrisponde al fuso orario locale e chiamare ConvertTimeToUtc(DateTime, TimeZoneInfo) metodo.Applications running on Windows XPWindows XP that require historically accurate local date and time calculations must work around this behavior by using the FindSystemTimeZoneById(String) method to retrieve a TimeZoneInfo object that corresponds to the local time zone and calling its ConvertTimeToUtc(DateTime, TimeZoneInfo) method.

Nell'esempio seguente viene illustrata la differenza tra ToUniversalTime() i ConvertTimeToUtc(DateTime, TimeZoneInfo) metodi e in Windows XPWindows XP un sistema negli Stati Uniti fuso orario Pacifico (Stati Uniti).The following example illustrates the difference between the ToUniversalTime() and ConvertTimeToUtc(DateTime, TimeZoneInfo) methods on a Windows XPWindows XP system in the U.S. Pacific Time zone. Le prime due chiamate al metodo applicano la regola di rettifica del fuso orario corrente (che è stata applicata in 2007) a una data in 2006.The first two method calls apply the current time zone adjustment rule (which went into effect in 2007) to a date in 2006. La regola di rettifica corrente consente la transizione all'ora legale la seconda domenica di marzo. la regola precedente, che era attiva in 2006, fornita per la transizione all'ora legale che si verifica la prima domenica di aprile.The current adjustment rule provides for the transition to daylight saving time on the second Sunday of March; the previous rule, which was in effect in 2006, provided for the transition to daylight saving time to occur on the first Sunday of April. Solo la terza chiamata al metodo esegue accuratamente questa conversione cronologica di data e ora.Only the third method call accurately performs this historical date and time conversion.

[!code-csharpSystem.DateTime.ToUniversalTime#1] [!code-vbSystem.DateTime.ToUniversalTime#1][!code-csharpSystem.DateTime.ToUniversalTime#1] [!code-vbSystem.DateTime.ToUniversalTime#1]

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