Export (0) Print
Expand All

SortVersion Class

.NET Framework 4.5

Provides information about the version of Unicode used to compare and order strings.

System.Object
  System.Globalization.SortVersion

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

[SerializableAttribute]
public sealed class SortVersion : IEquatable<SortVersion>

The SortVersion type exposes the following members.

  NameDescription
Public methodSortVersionCreates a new instance of the SortVersion class.
Top

  NameDescription
Public propertyFullVersionGets the full version number of the SortVersion object.
Public propertySortIdGets a globally unique identifier for this SortVersion object.
Top

  NameDescription
Public methodEquals(Object)Returns a value that indicates whether this SortVersion instance is equal to a specified object. (Overrides Object.Equals(Object).)
Public methodEquals(SortVersion)Returns a value that indicates whether this SortVersion instance is equal to a specified SortVersion object.
Public methodGetHashCodeReturns a hash code for this instance. (Overrides Object.GetHashCode().)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Top

  NameDescription
Public operatorStatic memberEqualityIndicates whether two SortVersion instances are equal.
Public operatorStatic memberInequalityIndicates whether two SortVersion instances are not equal.
Top

From the .NET Framework 2.0 Service Pack 1 through the .NET Framework 4, each version of the.NET Framework has included tables that contain sort weights and data on string normalization and that are based on a particular version of Unicode. In the .NET Framework 4.5, the presence of these tables depends on the operating system:

  • On Windows 7 and previous versions of the Windows operating system, the tables continue to be used for comparing and ordering strings.

  • On Windows 8, the .NET Framework delegates string comparison and ordering operations to the operating system.

Consequently, the result of a string comparison can depend not only on the .NET Framework version, but also on the operating system version, as the following table shows.

.NET Framework version

Operating system

Unicode version

.NET Framework 4

All operating systems

Unicode 5.0

.NET Framework 4.5

Windows 7

Unicode 5.0

.NET Framework 4.5

Windows 8

Unicode 6.0

On Windows 8, because the version of Unicode used in string comparison and ordering depends on the version of the operating system, the results of string comparison may differ even for applications that run on a specific version of the .NET Framework.

The SortVersion class provides information about the Unicode version used by the .NET Framework for string comparison and ordering. It enables developers to write applications that can detect and successfully handle changes in the version of Unicode that is used to compare and sort an application's strings.

You can instantiate a SortVersion object in two ways:

  • By calling the SortVersion constructor, which instantiates a new SortVersion object based on a version number and sort ID. This constructor is most useful when recreating a SortVersion object from saved data.

  • By retrieving the value of the CompareInfo.Version property. This property provides information about the Unicode version used by the .NET Framework on which the application is running.

The SortVersion class has two properties, FullVersion and SortId, that indicate the Unicode version and the specific culture used for string comparison. The FullVersion property is an arbitrary numeric value that reflects the Unicode version used for string comparison, and the SortId property is an arbitrary Guid that reflects the culture whose conventions are used for string comparison. The values of these two properties are important only when you compare two SortVersion objects by using the Equals method, the Equality operator, or the Inequality operator.

You typically use a SortVersion object when saving or retrieving some form of culture-sensitive, ordered string data, such as indexes or the literal strings themselves. This requires the following steps:

  1. When the ordered string data is saved, the FullVersion and SortId property values are also saved.

  2. When the ordered string data is retrieved, you can recreate the SortVersion object used for ordering the strings by calling the SortVersion constructor.

  3. This newly instantiated SortVersion object is compared with a SortVersion object that reflects the culture whose conventions are used to order the string data.

  4. If the two SortVersion objects are not equal, the string data must be reordered.

The example provides an illustration.

The following example contains a portion of the source code from an application that uses the SortVersion class to ensure that the native names of RegionInfo objects are ordered appropriately for the current system and current culture. It uses the BinaryReader and BinaryWriter objects to store and retrieve ordered data from a data file named Regions.dat rather than retrieving and ordering data each time the application is run. The example first checks to determine whether the data file exists. If it does not, it creates the data and sets the reindex flag, which indicates that the data must be resorted and saved again. Otherwise, it retrieves the data and compares the saved SortVersion object with the SortVersion object for the current culture on the current system. If they are not equal, or if the reindex flag had been set previously, it resorts the RegionInfo data.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Text;

public class Example : IComparer
{
   private const string FILENAME = @".\Regions.dat";

   private struct Region
   {
      internal Region(string id, string name) 
      {
         this.Id = id;
         this.NativeName = name;
      }

      public string Id;
      public string NativeName;

      public override string ToString()
      {
         return this.NativeName;
      }
   }

   public static void Main()
   {
      bool reindex = false;

      Region[] regions;
      SortVersion ver = null;

      // If the data has not been saved, create it. 
      if (! File.Exists(FILENAME)) { 
         regions = GenerateData();
         ver = CultureInfo.CurrentCulture.CompareInfo.Version;  
         reindex = true;
      }
      // Retrieve the existing data. 
      else {
         regions = RestoreData(out ver);
      }

      // Determine whether the current ordering is valid; if not, reorder. 
      if (reindex || ver != CultureInfo.CurrentCulture.CompareInfo.Version) { 
         Array.Sort(regions, new Example());      
         // Save newly reordered data.
         SaveData(regions);
      }

      // Continue with application...
   }

   private static Region[] GenerateData()
   {
      List<Region> regions = new List<Region>();

      foreach (var culture in CultureInfo.GetCultures(CultureTypes.AllCultures)) {
         if (culture.IsNeutralCulture | culture.Equals(CultureInfo.InvariantCulture))
            continue;

         RegionInfo region = new RegionInfo(culture.Name);
         regions.Add(new Region(region.Name, region.NativeName));
      }
      return regions.ToArray();
   }

   private static Region[] RestoreData(out SortVersion ver)
   {
      List<Region> regions = new List<Region>();

      BinaryReader rdr = new BinaryReader(File.Open(FILENAME, FileMode.Open));

      int sortVer = rdr.ReadInt32();
      Guid sortId = Guid.Parse(rdr.ReadString());
      ver = new SortVersion(sortVer, sortId);

      string id, name;
      while (rdr.PeekChar() != -1) {
         id = rdr.ReadString();
         name = rdr.ReadString();
         regions.Add(new Region(id, name));      
      }
      return regions.ToArray();
   }

   private static void SaveData(Region[] regions)
   {
      SortVersion ver = CultureInfo.CurrentCulture.CompareInfo.Version;

      BinaryWriter wrtr = new BinaryWriter(File.Open(FILENAME, FileMode.Create));
      wrtr.Write(ver.FullVersion); 
      wrtr.Write(ver.SortId.ToString()); 

      foreach (var region in regions) {
         wrtr.Write(region.Id);
         wrtr.Write(region.NativeName);
      }
      wrtr.Close();
   }

   public int Compare(object o1, object o2)
   {
        // Assume that all casts succeed.
        Region r1 = (Region) o1;
        Region r2 = (Region) o2;

        return String.Compare(r1.NativeName, r2.NativeName, 
                              StringComparison.CurrentCulture);        
   }
}

.NET Framework

Supported in: 4.5

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Show:
© 2014 Microsoft