Comparer Class

Comparer Class


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

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


public sealed class Comparer : IComparer, ISerializable


Initializes a new instance of the Comparer class using the specified System.Globalization.CultureInfo.

System_CAPS_pubmethodCompare(Object, Object)

Performs a case-sensitive comparison of two objects of the same type and returns a value indicating whether one is less than, equal to, or greater than the other.


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetObjectData(SerializationInfo, StreamingContext)

Populates a SerializationInfo object with the data required for serialization.


Gets the Type of the current instance.(Inherited from Object.)


Returns a string that represents the current object.(Inherited from Object.)


Represents an instance of Comparer that is associated with the Thread.CurrentCulture of the current thread. This field is read-only.


Represents an instance of Comparer that is associated with CultureInfo.InvariantCulture. This field is read-only.

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 Globalizing and Localizing .NET Framework Applications.

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


Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1

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

Return to top
© 2015 Microsoft