DateTime.ToUniversalTime 方法
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
将当前 DateTime 对象的值转换为协调世界时 (UTC)。
public:
DateTime ToUniversalTime();public DateTime ToUniversalTime ();member this.ToUniversalTime : unit -> DateTimePublic Function ToUniversalTime () As DateTime返回
其Kind属性为 Utc的 对象，其值与当前DateTime对象的值等效于 UTC;如果转换的值太大而无法由DateTime对象表示，则为 DateTime.MaxValue;如果转换的值太小而无法由 DateTime 对象表示，则为 DateTime.MinValue。
示例
下面的示例演示 ToUniversalTime 方法。
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.
open System
printfn "Enter a date and time."
try
let strDateTime = stdin.ReadLine()
let localDateTime = DateTime.Parse strDateTime
let univDateTime = localDateTime.ToUniversalTime()
printfn $"{localDateTime} local time is {univDateTime} universal time."
with :? FormatException ->
printfn "Invalid format."
printfn "Enter a date and time in universal time."
try
let strDateTime = stdin.ReadLine()
let univDateTime = DateTime.Parse strDateTime
let localDateTime = univDateTime.ToLocalTime()
printfn $"{univDateTime} universal time is {localDateTime} local time."
with :? FormatException ->
printfn "Invalid format."
// 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.
以下示例使用 SpecifyKind 方法演示 属性如何影响 KindToLocalTime 和 ToUniversalTime 转换方法。
// This code example demonstrates the DateTime Kind, Now, and
// UtcNow properties, and the SpecifyKind(), ToLocalTime(),
// and ToUniversalTime() methods.
open System
// 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.
let datePatt = @"M/d/yyyy hh:mm:ss tt"
let display title (inputDt: DateTime) =
// Display the original DateTime.
let dispDt = inputDt
let dtString = dispDt.ToString datePatt
printfn $"%s{title} {dtString}, Kind = {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.
let dispDt = inputDt.ToLocalTime()
let dtString = dispDt.ToString datePatt
printfn $" ToLocalTime: {dtString}, Kind = {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.
let dispDt = inputDt.ToUniversalTime()
let dtString = dispDt.ToString datePatt
printfn $" ToUniversalTime: {dtString}, Kind = {dispDt.Kind}\n"
// Display the value and Kind property for DateTime.Now and DateTime.UtcNow.
let displayNow title (inputDt: DateTime) =
let dtString = inputDt.ToString datePatt
printfn $"%s{title} {dtString}, Kind = {inputDt.Kind}"
[<EntryPoint>]
let main _ =
// Get the date and time for the current moment, adjusted
// to the local time zone.
let saveNow = DateTime.Now
// Get the date and time for the current moment expressed
// as coordinated universal time (UTC).
let saveUtcNow = DateTime.UtcNow
// Display the value and Kind property of the current moment
// expressed as UTC and local time.
displayNow "UtcNow: .........." saveUtcNow
displayNow "Now: ............." saveNow
printfn ""
// Change the Kind property of the current moment to
// DateTimeKind.Utc and display the result.
let myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Utc)
display "Utc: ............." myDt
// Change the Kind property of the current moment to
// DateTimeKind.Local and display the result.
let myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Local)
display "Local: ..........." myDt
// Change the Kind property of the current moment to
// DateTimeKind.Unspecified and display the result.
let myDt = DateTime.SpecifyKind(saveNow, DateTimeKind.Unspecified)
display "Unspecified: ....." myDt
0
// 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 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.
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
' 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 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
End Class
'
'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
'
注解
协调世界时 (UTC) 等于本地时间减去 UTC 偏移量。 有关 UTC 偏移量的详细信息，请参阅 TimeZoneInfo.GetUtcOffset。 转换还考虑了应用于当前 DateTime 对象所表示时间的夏令时规则。
重要
在 Windows XP 系统上，方法 ToUniversalTime 在从本地时间转换为 UTC 时仅识别当前调整规则。 因此，在当前调整规则生效之前的时间段的转换可能无法准确反映本地时间和 UTC 之间的差异。
从 .NET Framework 版本 2.0 开始，方法返回ToUniversalTime的值由Kind当前 DateTime 对象的 属性确定。 下表描述了可能的结果。
| 种类 | 结果 |
|---|---|
| Utc | 不执行任何转换。 |
| Local | DateTime当前对象转换为 UTC。 |
| Unspecified | 假定当前 DateTime 对象是本地时间，并且转换的执行方式就像 Kind 是 Local一样。 |
注意
方法 ToUniversalTime 将 DateTime 值从本地时间转换为 UTC。 若要将非本地时区中的时间转换为 UTC，请使用 TimeZoneInfo.ConvertTimeToUtc(DateTime, TimeZoneInfo) 方法。 若要转换与 UTC 的偏移量已知的时间，请使用 ToUniversalTime 方法。
如果日期和时间实例值不明确，则此方法假定它是标准时间。 (不明确时间是可以映射到本地时区中的标准时间或夏令时的时间) 如果日期和时间实例值无效，此方法只需从本地时区的 UTC 偏移量中减去本地时间即可返回 UTC。 (无效时间是由于应用夏令时调整规则而不存在的时间。)
调用方说明
ToUniversalTime()方法有时用于将本地时间转换为 UTC。 ToLocalTime()然后调用 方法以还原原始本地时间。 但是，如果原始时间表示本地时区中的无效时间，则这两个本地时间值将不相等。 有关其他信息和示例，请参阅 ToLocalTime() 方法。
在 Windows XP 系统上， ToUniversalTime() 方法仅识别本地时区的当前调整规则，该规则适用于所有日期，包括下层日期 (即早于当前调整规则) 开始日期的日期。 在 Windows XP 上运行且需要历史准确本地日期和时间计算的应用程序必须通过使用 FindSystemTimeZoneById(String) 方法检索 TimeZoneInfo 对应于本地时区的对象并调用其 ConvertTimeToUtc(DateTime, TimeZoneInfo) 方法来解决此行为。
以下示例演示了美国太平洋时区中 Windows XP 系统上 的 和 ConvertTimeToUtc(DateTime, TimeZoneInfo) 方法之间的差异ToUniversalTime()。 前两个方法调用将当前时区调整规则 (于 2007 年生效，) 到 2006 年的某个日期。 现行调整规则规定在3月第二个星期日过渡到夏令时：上一条规则于2006年生效，规定在4月的第一个星期日过渡到夏令时。 只有第三个方法调用才能准确执行此历史日期和时间转换。
using System;
public class Example
{
public static void Main()
{
DateTime date1 = new DateTime(2006, 3, 21, 2, 0, 0);
Console.WriteLine(date1.ToUniversalTime());
Console.WriteLine(TimeZoneInfo.ConvertTimeToUtc(date1));
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");
Console.WriteLine(TimeZoneInfo.ConvertTimeToUtc(date1, tz));
}
}
// The example displays the following output on Windows XP systems:
// 3/21/2006 9:00:00 AM
// 3/21/2006 9:00:00 AM
// 3/21/2006 10:00:00 AM
open System
let date1 = DateTime(2006, 3, 21, 2, 0, 0)
printfn $"{date1.ToUniversalTime()}"
printfn $"{TimeZoneInfo.ConvertTimeToUtc date1}"
let tz = TimeZoneInfo.FindSystemTimeZoneById "Pacific Standard Time"
printfn $"{TimeZoneInfo.ConvertTimeToUtc(date1, tz)}"
// The example displays the following output on Windows XP systems:
// 3/21/2006 9:00:00 AM
// 3/21/2006 9:00:00 AM
// 3/21/2006 10:00:00 AM
Module Example
Public Sub Main()
Dim date1 As Date = #3/21/2006 2:00AM#
Console.WriteLine(date1.ToUniversalTime())
Console.WriteLine(TimeZoneInfo.ConvertTimeToUtc(date1))
Dim tz As TimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time")
Console.WriteLine(TimeZoneInfo.ConvertTimeToUtc(date1, tz))
End Sub
End Module
' The example displays the following output on Windows XP systems:
' 3/21/2006 9:00:00 AM
' 3/21/2006 9:00:00 AM
' 3/21/2006 10:00:00 AM
