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TimeZoneInfo.HasSameRules Method

Indicates whether the current object and another TimeZoneInfo object have the same adjustment rules.

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

public bool HasSameRules(
	TimeZoneInfo other


Type: System.TimeZoneInfo
A second object to compare with the current TimeZoneInfo object.

Return Value

Type: System.Boolean
true if the two time zones have identical adjustment rules and an identical base offset; otherwise, false.


The other parameter is null.

Like the TimeZoneInfo.Equals(TimeZoneInfo) method, the HasSameRules method indicates whether two time zones have the same base offset (as defined by the BaseUtcOffset property) and the same adjustment rules. Unlike the TimeZoneInfo.Equals(TimeZoneInfo) method, HasSameRules does not compare time zone identifiers (as defined by the Id property).

Typically, a number of time zones defined in the registry have the same offset from Coordinated Universal Time (UTC) and the same adjustment rules. The following example displays a list of these time zones to the console.

ReadOnlyCollection<TimeZoneInfo> timeZones = TimeZoneInfo.GetSystemTimeZones();
TimeZoneInfo[] timeZoneArray = new TimeZoneInfo[timeZones.Count];
timeZones.CopyTo(timeZoneArray, 0);
// Iterate array from top to bottom
for (int ctr = timeZoneArray.GetUpperBound(0); ctr >= 1; ctr--)
   // Get next item from top
   TimeZoneInfo thisTimeZone = timeZoneArray[ctr];
   for (int compareCtr = 0; compareCtr <= ctr - 1; compareCtr++)
      // Determine if time zones have the same rules
      if (thisTimeZone.HasSameRules(timeZoneArray[compareCtr]))
         Console.WriteLine("{0} has the same rules as {1}", 

.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, 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.