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Comparer Class

Compares two objects for equivalence, where string comparisons are case-sensitive.

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

[SerializableAttribute] 
[ComVisibleAttribute(true)] 
public sealed class Comparer : IComparer, ISerializable
/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
public final class Comparer implements IComparer, ISerializable
SerializableAttribute 
ComVisibleAttribute(true) 
public final class Comparer implements IComparer, ISerializable
Not applicable.

This class is the default implementation of the IComparer interface. The CaseInsensitiveComparer class is the implementation of the IComparer interface that performs case-insensitive string comparisons.

Comparison procedures use the Thread.CurrentCulture of the current thread unless otherwise specified. String comparisons might have different results depending on the culture. For more information on culture-specific comparisons, see the System.Globalization namespace and Encoding and Localization.

The following code example shows how Compare returns different values depending on the culture associated with the Comparer.

using System;
using System.Collections;
using System.Globalization;


public class SamplesComparer  {

   public static void Main()  {

      // Creates the strings to compare.
      String str1 = "llegar";
      String str2 = "lugar";
      Console.WriteLine( "Comparing \"{0}\" and \"{1}\" ...", str1, str2 );

      // Uses the DefaultInvariant Comparer.
      Console.WriteLine( "   Invariant Comparer: {0}", Comparer.DefaultInvariant.Compare( str1, str2 ) );

      // Uses the Comparer based on the culture "es-ES" (Spanish - Spain, international sort).
      Comparer myCompIntl = new Comparer( new CultureInfo( "es-ES", false ) );
      Console.WriteLine( "   International Sort: {0}", myCompIntl.Compare( str1, str2 ) );

      // Uses the Comparer based on the culture identifier 0x040A (Spanish - Spain, traditional sort).
      Comparer myCompTrad = new Comparer( new CultureInfo( 0x040A, false ) );
      Console.WriteLine( "   Traditional Sort  : {0}", myCompTrad.Compare( str1, str2 ) );

   }

}

/*
This code produces the following output.

Comparing "llegar" and "lugar" ...
   Invariant Comparer: -1
   International Sort: -1
   Traditional Sort  : 1

*/

import System.* ;
import System.Collections.*;
import System.Globalization.*;

public class SamplesComparer
{
    public static void main(String[] args)
    {
        // Creates the strings to compare.
        String str1 = "llegar";
        String str2 = "lugar";
        Console.WriteLine("Comparing \"{0}\" and \"{1}\" ...", str1, str2);
      
        // Uses the DefaultInvariant Comparer.
        Console.WriteLine("   Invariant Comparer: {0}", 
            (Int32)Comparer.DefaultInvariant.Compare(str1, str2));

        // Uses the Comparer based on the culture "es-ES" (Spanish - Spain, 
        // international sort).
        Comparer myCompIntl = new Comparer(new CultureInfo("es-ES", false));
        Console.WriteLine("   International Sort: {0}", 
            (Int32)myCompIntl.Compare(str1, str2));

        // Uses the Comparer based on the culture identifier 0x040A 
        // (Spanish - Spain, traditional sort).
        Comparer myCompTrad = new Comparer(new CultureInfo(0x40A, false));
        Console.WriteLine("   Traditional Sort  : {0}",
            (Int32)myCompTrad.Compare(str1, str2));
    } //main
} //SamplesComparer

/*
This code produces the following output.

Comparing "llegar" and "lugar" ...
   Invariant Comparer: -1
   International Sort: -1
   Traditional Sort  : 1

*/

System.Object
  System.Collections.Comparer

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

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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