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Comparer.Compare Method

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.

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

public int Compare(
	Object a,
	Object b
)

Parameters

a
Type: System.Object

The first object to compare.

b
Type: System.Object

The second object to compare.

Return Value

Type: System.Int32

Value

Condition

Less than zero

a is less than b.

Zero

a equals b.

Greater than zero

a is greater than b.

Implements

IComparer.Compare(Object, Object)

ExceptionCondition
ArgumentException

Neither a nor b implements the IComparable interface.

-or-

a and b are of different types and neither one can handle comparisons with the other.

If a implements IComparable, then a. CompareTo (b) is returned; otherwise, if b implements IComparable, then the negated result of b. CompareTo (a) is returned.

Comparing null with any type is allowed and does not generate an exception when using IComparable. When sorting, null is considered to be less than any other object.

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

*/

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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