System.TimeZone.IsDaylightSavingTime 方法 (DateTime)
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方法描述
返回一个值，用以指示指定日期和时间是否处于夏时制期间。
语法定义(C# System.TimeZone.IsDaylightSavingTime 方法 (DateTime) 的用法)
public virtual bool IsDaylightSavingTime( DateTime time )
参数/返回值
| 参数值/返回值 | 参数类型/返回类型 | 参数描述/返回描述 |
|---|---|---|
| time | System-DateTime | 日期和时间。 |
| 返回值 | System.Boolean | 如果 time 处于夏时制期间，则为 true；否则为 false。 |
提示和注释
要应用夏时制期间的年份是从 time 参数派生的。
由于 TimeZone 类支持单个夏时制调整规则，因此 IsDaylightSavingTime(DateTime) 方法会将当前的调整规则应用到任何日期，而无论调整规则在该日期是否有效。 假定操作系统本身具有准确的历史夏时制数据，则通过使用 TimeZoneInfo.IsDaylightSavingTime 方法可以获得更准确的结果。 应尽可能使用 TimeZoneInfo.IsDaylightSavingTime 方法。
System.TimeZone.IsDaylightSavingTime 方法 (DateTime)例子
下面的示例使用 IsDaylightSavingTime 方法，确定选定的日期是否在任何年份都属于夏时制时间。
// Example of the TimeZone.IsDaylightSavingTime( DateTime ),
// TimeZone.IsDaylightSavingTime( DateTime, DaylightTime ), and
// TimeZone.ToUniversalTime( DateTime ) methods.
using System;
using System.Globalization;
class DaylightTimeDemo
{
static void Main( )
{
const string headFmt = "{0,-22}{1,-10}{2,-10}{3,-10}{4}";
// Get the local time zone and a base local time.
TimeZone localZone = TimeZone.CurrentTimeZone;
DateTime localTime = new DateTime( 2001, 1, 1 );
Console.WriteLine( "This example of \n" +
" TimeZone.IsDaylightSavingTime( DateTime ), \n" +
" TimeZone.IsDaylightSavingTime( " +
"DateTime, DaylightTime ), and \n" +
" TimeZone.ToUniversalTime( DateTime )\n" +
"generates the following output, which varies " +
"depending on the \ntime zone in which it is run.\n" );
Console.WriteLine( "The example creates several local " +
"times and the corresponding \nCoordinated Universal " +
"Times (UTC) and shows if they occur in \ndaylight " +
"saving time (DST), both for specified years " +
"and for \nany year.\n" );
Console.WriteLine( "Local time: {0}\n",
localZone.StandardName );
Console.WriteLine( headFmt, "Local Date and Time", "2001 DST?",
"2002 DST?", "Any DST?", "Corresponding UTC" );
Console.WriteLine( headFmt, "-------------------", "---------",
"---------", "--------", "-----------------" );
// Create DaylightTime objects for specific years.
DaylightTime daylight2001 =
localZone.GetDaylightChanges( 2001 );
DaylightTime daylight2002 =
localZone.GetDaylightChanges( 2002 );
// Generate several local times.
for( int loopX = 0; loopX <= 10; loopX++ )
{
// Calculate the corresponding UTC.
DateTime utcTime =
localZone.ToUniversalTime( localTime );
// Show if dates and times occur in daylight saving
// time, for specified years and for any year.
Console.WriteLine( "{0,-22:yyyy-MM-dd HH:mm}" +
"{1,-10}{2,-10}{3,-10}{4:yyyy-MM-dd HH:mm}",
localTime,
TimeZone.IsDaylightSavingTime(
localTime, daylight2001 ),
TimeZone.IsDaylightSavingTime(
localTime, daylight2002 ),
localZone.IsDaylightSavingTime( localTime ),
utcTime );
// Advance to another local time.
localTime = localTime.AddDays( 109.1 );
}
}
}
/*
This example of
TimeZone.IsDaylightSavingTime( DateTime ),
TimeZone.IsDaylightSavingTime( DateTime, DaylightTime ), and
TimeZone.ToUniversalTime( DateTime )
generates the following output, which varies depending on the
time zone in which it is run.
The example creates several local times and the corresponding
Coordinated Universal Times (UTC) and shows if they occur in
daylight saving time (DST), both for specified years and for
any year.
Local time: Pacific Standard Time
Local Date and Time 2001 DST? 2002 DST? Any DST? Corresponding UTC
------------------- --------- --------- -------- -----------------
2001-01-01 00:00 False False False 2001-01-01 08:00
2001-04-20 02:24 True False True 2001-04-20 09:24
2001-08-07 04:48 True False True 2001-08-07 11:48
2001-11-24 07:12 False False False 2001-11-24 15:12
2002-03-13 09:36 False False False 2002-03-13 17:36
2002-06-30 12:00 False True True 2002-06-30 19:00
2002-10-17 14:24 False True True 2002-10-17 21:24
2003-02-03 16:48 False False False 2003-02-04 00:48
2003-05-23 19:12 False False True 2003-05-24 02:12
2003-09-09 21:36 False False True 2003-09-10 04:36
2003-12-28 00:00 False False False 2003-12-28 08:00
*/
版本信息
.NET Framework 受以下版本支持：4、3.5、3.0、2.0、1.1、1.0 .NET Framework Client Profile 受以下版本支持：4、3.5 SP1
适用平台
Windows 7, Windows Vista SP1 或更高版本, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008（不支持服务器核心）, Windows Server 2008 R2（支持 SP1 或更高版本的服务器核心）, Windows Server 2003 SP2 .NET Framework 并不是对每个平台的所有版本都提供支持。有关支持的版本的列表，请参见.NET Framework 系统要求。
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