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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
)
public final int Compare (
	Object a, 
	Object b
)
public final function Compare (
	a : Object, 
	b : Object
) : int
Not applicable.

Parameters

a

The first object to compare.

b

The second object to compare.

Return Value

Value

Condition

Less than zero

a is less than b.

Zero

a equals b.

Greater than zero

a is greater than b.

Exception typeCondition

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 a null reference (Nothing in Visual Basic) with any type is allowed and does not generate an exception when using IComparable. When sorting, a null reference (Nothing in Visual Basic) 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

*/

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

*/

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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