Export (0) Print
Expand All

Comparer Class

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

For a list of all members of this type, see Comparer Members.

System.Object
   System.Collections.Comparer

[Visual Basic]
<Serializable>
NotInheritable Public Class Comparer
   Implements IComparer
[C#]
[Serializable]
public sealed class Comparer : IComparer
[C++]
[Serializable]
public __gc __sealed class Comparer : public IComparer
[JScript]
public
   Serializable
class Comparer implements IComparer

Thread Safety

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

Remarks

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.

String comparisons might have different results depending on the culture. For more information on culture-specific comparisons, see the System.Globalization namespace and Developing World-Ready Applications.

Example

[Visual Basic, C#, C++] The following code example shows how Compare returns different values depending on the culture associated with the Comparer.

[Visual Basic] 
Imports System
Imports System.Collections
Imports System.Globalization

Public Class SamplesComparer

   Public Shared Sub Main()

      ' Creates the strings to compare.
      Dim str1 As [String] = "llegar"
      Dim str2 As [String] = "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).
      Dim myCompIntl As 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).
      Dim myCompTrad As New Comparer(New CultureInfo(&H40A, False))
      Console.WriteLine("   Traditional Sort  : {0}", myCompTrad.Compare(str1, str2))

   End Sub 'Main 

End Class 'SamplesComparer


'This code produces the following output.
'
'Comparing "llegar" and "lugar" ...
'   Invariant Comparer: -1
'   International Sort: -1
'   Traditional Sort  : 1


[C#] 
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

*/

[C++] 
#using <mscorlib.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Globalization;

int main()  {

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

    // Uses the DefaultInvariant Comparer.
    Console::WriteLine(S"   Invariant Comparer: {0}", __box(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(S"   International Sort: {0}", __box(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(S"   Traditional Sort  : {0}", __box(myCompTrad->Compare(str1, str2)));
}

/*
This code produces the following output.

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

*/

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Collections

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: Mscorlib (in Mscorlib.dll)

See Also

Comparer Members | System.Collections Namespace | IComparer | IComparable | CaseInsensitiveComparer | System.Globalization.CompareInfo | Thread.CurrentCulture | System.Globalization.CultureInfo

Show:
© 2014 Microsoft