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TimeZone.IsDaylightSavingTime Method (DateTime)

Returns a value indicating whether the specified date and time is within a daylight saving time period.

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

abstract IsDaylightSavingTime : 
        time:DateTime -> bool 
override IsDaylightSavingTime : 
        time:DateTime -> bool 


Type: System.DateTime
A date and time.

Return Value

Type: System.Boolean
true if time is in a daylight saving time period; otherwise, false.

The year to which the daylight saving time period applies is derived from the time parameter.

Because the TimeZone class supports a single daylight saving time adjustment rule, the IsDaylightSavingTime(DateTime) method applies the current adjustment rule to any date, regardless of whether the adjustment rule was in effect on that date. Assuming that the operating system itself has accurate historic daylight saving time data, a more accurate result is available by using the TimeZoneInfo.IsDaylightSavingTime method. Whenever possible, use the TimeZoneInfo.IsDaylightSavingTime method.

The following example uses the IsDaylightSavingTime method to determine whether selected dates are within daylight saving time for any year.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.