DateTime.Now 属性

定义

获取一个 DateTime 对象,该对象设置为此计算机上的当前日期和时间,表示为本地时间。

public:
 static property DateTime Now { DateTime get(); };
public static DateTime Now { get; }
member this.Now : DateTime
Public Shared ReadOnly Property Now As DateTime

属性值

DateTime

其值为当前日期和时间的对象。

示例

以下示例使用 NowUtcNow 属性检索当前本地日期和时间以及当前通用协调 (UTC) 日期和时间。 然后,它使用多个区域性的格式设置约定来显示字符串及其属性的值 Kind

using namespace System;
using namespace System::Globalization;

void main()
{
   DateTime localDate = DateTime::Now;
   DateTime utcDate = DateTime::UtcNow;
   array<String^>^ cultureNames = { "en-US", "en-GB", "fr-FR",
                                    "de-DE", "ru-RU" } ;

   for each (String^ cultureName in cultureNames) {
      CultureInfo^ culture = gcnew CultureInfo(cultureName);
      Console::WriteLine("{0}:", culture->NativeName);
      Console::WriteLine("   Local date and time: {0}, {1:G}",
                         localDate.ToString(culture), localDate.Kind);
      Console::WriteLine("   UTC date and time: {0}, {1:G}\n",
                         utcDate.ToString(culture), utcDate.Kind);
   }
}
// The example displays the following output:
//       English (United States):
//          Local date and time: 6/19/2015 10:35:50 AM, Local
//          UTC date and time: 6/19/2015 5:35:50 PM, Utc
//
//       English (United Kingdom):
//          Local date and time: 19/06/2015 10:35:50, Local
//          UTC date and time: 19/06/2015 17:35:50, Utc
//
//       français (France):
//          Local date and time: 19/06/2015 10:35:50, Local
//          UTC date and time: 19/06/2015 17:35:50, Utc
//
//       Deutsch (Deutschland):
//          Local date and time: 19.06.2015 10:35:50, Local
//          UTC date and time: 19.06.2015 17:35:50, Utc
//
//       русский (Россия):
//          Local date and time: 19.06.2015 10:35:50, Local
//          UTC date and time: 19.06.2015 17:35:50, Utc
using System;
using System.Globalization;

public class Example
{
   public static void Main()
   {
      DateTime localDate = DateTime.Now;
      DateTime utcDate = DateTime.UtcNow;
      String[] cultureNames = { "en-US", "en-GB", "fr-FR",
                                "de-DE", "ru-RU" } ;

      foreach (var cultureName in cultureNames) {
         var culture = new CultureInfo(cultureName);
         Console.WriteLine("{0}:", culture.NativeName);
         Console.WriteLine("   Local date and time: {0}, {1:G}",
                           localDate.ToString(culture), localDate.Kind);
         Console.WriteLine("   UTC date and time: {0}, {1:G}\n",
                           utcDate.ToString(culture), utcDate.Kind);
      }
   }
}
// The example displays the following output:
//       English (United States):
//          Local date and time: 6/19/2015 10:35:50 AM, Local
//          UTC date and time: 6/19/2015 5:35:50 PM, Utc
//
//       English (United Kingdom):
//          Local date and time: 19/06/2015 10:35:50, Local
//          UTC date and time: 19/06/2015 17:35:50, Utc
//
//       français (France):
//          Local date and time: 19/06/2015 10:35:50, Local
//          UTC date and time: 19/06/2015 17:35:50, Utc
//
//       Deutsch (Deutschland):
//          Local date and time: 19.06.2015 10:35:50, Local
//          UTC date and time: 19.06.2015 17:35:50, Utc
//
//       русский (Россия):
//          Local date and time: 19.06.2015 10:35:50, Local
//          UTC date and time: 19.06.2015 17:35:50, Utc
open System
open System.Globalization

let localDate = DateTime.Now
let utcDate = DateTime.UtcNow
let cultureNames = 
    [ "en-US"; "en-GB"; "fr-FR"; "de-DE"; "ru-RU" ] 

for cultureName in cultureNames do
    let culture = CultureInfo cultureName
    printfn $"{culture.NativeName}:"
    printfn $"   Local date and time: {localDate.ToString culture}, {localDate.Kind:G}"
    printfn $"   UTC date and time: {utcDate.ToString culture}, {utcDate.Kind:G}\n"

// The example displays the following output:
//       English (United States):
//          Local date and time: 6/19/2015 10:35:50 AM, Local
//          UTC date and time: 6/19/2015 5:35:50 PM, Utc
//
//       English (United Kingdom):
//          Local date and time: 19/06/2015 10:35:50, Local
//          UTC date and time: 19/06/2015 17:35:50, Utc
//
//       français (France):
//          Local date and time: 19/06/2015 10:35:50, Local
//          UTC date and time: 19/06/2015 17:35:50, Utc
//
//       Deutsch (Deutschland):
//          Local date and time: 19.06.2015 10:35:50, Local
//          UTC date and time: 19.06.2015 17:35:50, Utc
//
//       русский (Россия):
//          Local date and time: 19.06.2015 10:35:50, Local
//          UTC date and time: 19.06.2015 17:35:50, Utc
Imports System.Globalization

Module Example
   Public Sub Main()
      Dim localDate = DateTime.Now
      Dim utcDate = DateTime.UtcNow
      Dim cultureNames() As String = { "en-US", "en-GB", "fr-FR",
                                       "de-DE", "ru-RU" }

      For Each cultureName In cultureNames
         Dim culture As New CultureInfo(cultureName)
         Console.WriteLine("{0}:", culture.NativeName)
         Console.WriteLine("   Local date and time: {0}, {1:G}",
                           localDate.ToString(culture), localDate.Kind)
         Console.WriteLine("   UTC date and time: {0}, {1:G}",
                           utcDate.ToString(culture), utcDate.Kind)
         Console.WriteLine()
      Next
   End Sub
End Module
' The example displays the following output:
'       English (United States):
'          Local date and time: 6/19/2015 10:35:50 AM, Local
'          UTC date and time: 6/19/2015 5:35:50 PM, Utc
'
'       English (United Kingdom):
'          Local date and time: 19/06/2015 10:35:50, Local
'          UTC date and time: 19/06/2015 17:35:50, Utc
'
'       français (France):
'          Local date and time: 19/06/2015 10:35:50, Local
'          UTC date and time: 19/06/2015 17:35:50, Utc
'
'       Deutsch (Deutschland):
'          Local date and time: 19.06.2015 10:35:50, Local
'          UTC date and time: 19.06.2015 17:35:50, Utc
'
'       русский (Россия):
'          Local date and time: 19.06.2015 10:35:50, Local
'          UTC date and time: 19.06.2015 17:35:50, Utc

注解

Now 属性返回一个 DateTime 值,该值表示本地计算机上的当前日期和时间。 请注意,一个 DateTime 值之间存在差异,该值表示自 0001 年 1 月 1 日午夜以来经过的刻度数,以及该值 DateTime 的字符串表示形式,该值以特定于区域性的格式表示日期和时间值。 有关设置日期和时间值的格式的信息,请参阅 ToString 方法。 以下示例以多种区域性特定的格式显示短日期和时间字符串。

using namespace System;
using namespace System::Globalization;

void main()
{
   DateTime localDate = DateTime::Now;
   array<String^>^ cultureNames = { "en-US", "en-GB", "fr-FR",
                                    "de-DE", "ru-RU" };

   for each (String^ cultureName in cultureNames) {
      CultureInfo^ culture = gcnew CultureInfo(cultureName);
      Console::WriteLine("{0}: {1}", cultureName,
                         localDate.ToString(culture));
   }
}
// The example displays the following output:
//       en-US: 6/19/2015 10:03:06 AM
//       en-GB: 19/06/2015 10:03:06
//       fr-FR: 19/06/2015 10:03:06
//       de-DE: 19.06.2015 10:03:06
//       ru-RU: 19.06.2015 10:03:06
using System;
using System.Globalization;

public class Example
{
   public static void Main()
   {
      DateTime localDate = DateTime.Now;
      String[] cultureNames = { "en-US", "en-GB", "fr-FR",
                                "de-DE", "ru-RU" };

      foreach (var cultureName in cultureNames) {
         var culture = new CultureInfo(cultureName);
         Console.WriteLine("{0}: {1}", cultureName,
                           localDate.ToString(culture));
      }
   }
}
// The example displays the following output:
//       en-US: 6/19/2015 10:03:06 AM
//       en-GB: 19/06/2015 10:03:06
//       fr-FR: 19/06/2015 10:03:06
//       de-DE: 19.06.2015 10:03:06
//       ru-RU: 19.06.2015 10:03:06
open System
open System.Globalization

let localDate = DateTime.Now
let cultureNames = 
    [ "en-US"; "en-GB"; "fr-FR"; "de-DE"; "ru-RU" ]

for cultureName in cultureNames do
    let culture = CultureInfo cultureName
    printfn $"{cultureName}: {localDate.ToString culture}"

// The example displays the following output:
//       en-US: 6/19/2015 10:03:06 AM
//       en-GB: 19/06/2015 10:03:06
//       fr-FR: 19/06/2015 10:03:06
//       de-DE: 19.06.2015 10:03:06
//       ru-RU: 19.06.2015 10:03:06
Imports System.Globalization

Module Example
   Public Sub Main()
      Dim localDate = DateTime.Now
      Dim cultureNames() As String = { "en-US", "en-GB", "fr-FR",
                                       "de-DE", "ru-RU" }

      For Each cultureName In cultureNames
         Dim culture As New CultureInfo(cultureName)
         Console.WriteLine("{0}: {1}", cultureName,
                           localDate.ToString(culture))
      Next
   End Sub
End Module
' The example displays the following output:
'    en-US: 6/19/2015 10:03:06 AM
'    en-GB: 19/06/2015 10:03:06
'    fr-FR: 19/06/2015 10:03:06
'    de-DE: 19.06.2015 10:03:06
'    ru-RU: 19.06.2015 10:03:06

此属性的解析取决于系统计时器,具体取决于基础操作系统。 它通常介于 0.5 到 15 毫秒之间。 因此,在短时间间隔(如循环中)对属性的重复调用 Now 可能会返回相同的值。

Now 属性通常用于度量性能。 但是,由于分辨率低,它不适合用作基准测试工具。 更好的替代方法是使用 Stopwatch 类。

从 .NET Framework 版本 2.0 开始,返回值是DateTimeKind属性返回DateTimeKind.Local的值。

备注

还可以使用此属性 DateTimeOffset.Now 检索当前本地日期和时间。 它允许将本地时间明确表示为单一时间点,这反过来又使该时间值跨计算机可移植。

适用于

另请参阅