HasSameRules Method

TimeZoneInfo.HasSameRules Method

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

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

public bool HasSameRules(
	TimeZoneInfo other


Type: System.TimeZoneInfo

A second TimeZoneInfo 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}", 

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

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

.NET Framework

Supported in: 3.5

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