TimeZoneInfo.HasSameRules(TimeZoneInfo) Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

TimeZoneInfo.cs

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

public:
 bool HasSameRules(TimeZoneInfo ^ other);

public bool HasSameRules (TimeZoneInfo other);

member this.HasSameRules : TimeZoneInfo -> bool

Public Function HasSameRules (other As TimeZoneInfo) As Boolean

Parameters

other

TimeZoneInfo

A second object to compare with the current TimeZoneInfo object.

Returns

Boolean

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

Exceptions

ArgumentNullException

The other parameter is null.

Examples

Typically, a number of time zones defined in the registry on Windows and the ICU Library on Linux and macOS 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}", 
                           thisTimeZone.StandardName,
                           timeZoneArray[compareCtr].StandardName);
      }
   }
}

let timeZones = TimeZoneInfo.GetSystemTimeZones()
let timeZoneArray = Array.ofSeq timeZones
// Iterate array from top to bottom
for ctr = timeZoneArray.GetUpperBound 0 - 1 downto 0 do
    // Get next item from top
    let thisTimeZone = timeZoneArray[ctr]
    for compareCtr = 0 to ctr - 1 do
        // Determine if time zones have the same rules
        if thisTimeZone.HasSameRules timeZoneArray[compareCtr] then
            printfn $"{thisTimeZone.StandardName} has the same rules as {timeZoneArray[compareCtr].StandardName}"

Dim timeZones As ReadOnlyCollection(Of TimeZoneInfo) = TimeZoneInfo.GetSystemTimeZones()
Dim timeZoneArray(timeZones.Count - 1) As TimeZoneInfo
timeZones.CopyTo(timeZoneArray, 0) 
'Dim arrayPtr As Integer = 1
' Iterate array from top to bottom
For ctr As Integer = timeZoneArray.GetUpperBound(0) To 1 Step -1
   ' Get next item from top
   Dim thisTimeZone As TimeZoneInfo = timeZoneArray(ctr)
   For compareCtr As Integer = 0 To ctr - 1
      ' Determine if time zones have the same rules
      If thisTimeZone.HasSameRules(timeZoneArray(compareCtr)) Then
         Console.WriteLine("{0} has the same rules as {1}", _
                           thisTimeZone.StandardName, _
                           timeZoneArray(compareCtr).StandardName)
      End If                     
   Next      
Next

Remarks

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).