CompareInfo Class (System.Globalization)

.NET Framework Class Library

CompareInfo Class

Implements a set of methods for culture-sensitive string comparisons.

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

Syntax

Visual Basic (Declaration)

<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public Class CompareInfo _
    Implements IDeserializationCallback

Visual Basic (Usage)

Dim instance As CompareInfo

[SerializableAttribute]
[ComVisibleAttribute(true)]
public class CompareInfo : IDeserializationCallback

Visual C++

[SerializableAttribute]
[ComVisibleAttribute(true)]
public ref class CompareInfo : IDeserializationCallback

JScript

public class CompareInfo implements IDeserializationCallback

Remarks

The CultureInfo class includes a CompareInfo property that is an instance of this class. String..::.Compare uses the information in CultureInfo..::.CompareInfo to compare strings.

CompareInfo provides the GetCompareInfo method, instead of public constructors, to allow for late-bound access.

To create a CompareInfo object for any culture, the application should use the CultureInfo..::.CompareInfo property, or use the GetCompareInfo method.

Ignored Search Values

Comparison operations, such as those performed by the IndexOf or LastIndexOf methods, can yield unexpected results if the value to search for is ignored. The search value is ignored if it is an empty string (""), a character or string consisting of characters having code points that are not considered in the operation because of comparison options, or a value with code points that have no linguistic significance. If the search value for the IndexOf method is an empty string, for example, the return value is zero.

Security Considerations

If a security decision depends on a string comparison or a case change, the application should use the InvariantCulture to ensure that the behavior is consistent, regardless of the culture settings of the operating system.

Examples

The following code example shows how the CompareInfo object associated with a CultureInfo object affects string comparison.

Visual Basic

Imports System
Imports System.Text
Imports System.Globalization

NotInheritable Public Class App
    Shared Sub Main(ByVal args() As String) 
        Dim sign() As String = {"<", "=", ">"}

        ' The code below demonstrates how strings compare 
        ' differently for different cultures.
        Dim s1 As String = "Coté"
        Dim s2 As String = "coté"
        Dim s3 As String = "côte"

        ' Set sort order of strings for French in France.
        Dim ci As CompareInfo = New CultureInfo("fr-FR").CompareInfo
        Console.WriteLine("The LCID for {0} is {1}.", ci.Name, ci.LCID)

        ' Display the result using fr-FR Compare of Coté = coté.      
        Console.WriteLine("fr-FR Compare: {0} {2} {1}", _
                          s1, s2, sign((ci.Compare(s1, s2, CompareOptions.IgnoreCase) + 1)))

        ' Display the result using fr-FR Compare of coté > côte.
        Console.WriteLine("fr-FR Compare: {0} {2} {1}", _
                          s2, s3, sign((ci.Compare(s2, s3, CompareOptions.None) + 1)))

        ' Set sort order of strings for Japanese as spoken in Japan.
        ci = New CultureInfo("ja-JP").CompareInfo
        Console.WriteLine("The LCID for {0} is {1}.", ci.Name, ci.LCID)

        ' Display the result using ja-JP Compare of coté < côte. 
        Console.WriteLine("ja-JP Compare: {0} {2} {1}", _
                          s2, s3, sign((ci.Compare(s2, s3) + 1)))
    End Sub 'Main
End Class 'App

' This code produces the following output.
' 
' The LCID for fr-FR is 1036.
' fr-FR Compare: Coté = coté
' fr-FR Compare: coté > côte
' The LCID for ja-JP is 1041.
' ja-JP Compare: coté < côte

using System;
using System.Text;
using System.Globalization;

public sealed class App
{
    static void Main(string[] args)
    {
        String[] sign = new String[] { "<", "=", ">" };

        // The code below demonstrates how strings compare 
        // differently for different cultures.
        String s1 = "Coté", s2 = "coté", s3 = "côte";

        // Set sort order of strings for French in France.
        CompareInfo ci = new CultureInfo("fr-FR").CompareInfo;
        Console.WriteLine("The LCID for {0} is {1}.", ci.Name, ci.LCID);

        // Display the result using fr-FR Compare of Coté = coté.      
        Console.WriteLine("fr-FR Compare: {0} {2} {1}",
            s1, s2, sign[ci.Compare(s1, s2, CompareOptions.IgnoreCase) + 1]);

        // Display the result using fr-FR Compare of coté > côte.
        Console.WriteLine("fr-FR Compare: {0} {2} {1}",
            s2, s3, sign[ci.Compare(s2, s3, CompareOptions.None) + 1]);

        // Set sort order of strings for Japanese as spoken in Japan.
        ci = new CultureInfo("ja-JP").CompareInfo;
        Console.WriteLine("The LCID for {0} is {1}.", ci.Name, ci.LCID);

        // Display the result using ja-JP Compare of coté < côte. 
        Console.WriteLine("ja-JP Compare: {0} {2} {1}",
            s2, s3, sign[ci.Compare(s2, s3) + 1]);
    }
}

// This code produces the following output.
// 
// The LCID for fr-FR is 1036.
// fr-FR Compare: Coté = coté
// fr-FR Compare: coté > côte
// The LCID for ja-JP is 1041.
// ja-JP Compare: coté < côte

Visual C++

using namespace System;
using namespace System::Text;
using namespace System::Globalization;

int main()
{
    array<String^>^ sign = gcnew array<String^> { "<", "=", ">" };

    // The code below demonstrates how strings compare
    // differently for different cultures.
    String^ s1 = "Coté"; 
    String^ s2 = "coté";
    String^ s3 = "côte";

    // Set sort order of strings for French in France.
    CompareInfo^ ci = (gcnew CultureInfo("fr-FR"))->CompareInfo;
    Console::WriteLine(L"The LCID for {0} is {1}.", ci->Name, ci->LCID);

    // Display the result using fr-FR Compare of Coté = coté.
    Console::WriteLine(L"fr-FR Compare: {0} {2} {1}",
        s1, s2, sign[ci->Compare(s1, s2, CompareOptions::IgnoreCase) + 1]);

    // Display the result using fr-FR Compare of coté > côte.
    Console::WriteLine(L"fr-FR Compare: {0} {2} {1}",
        s2, s3, sign[ci->Compare(s2, s3, CompareOptions::None) + 1]);

    // Set sort order of strings for Japanese as spoken in Japan.
    ci = (gcnew CultureInfo("ja-JP"))->CompareInfo;
    Console::WriteLine(L"The LCID for {0} is {1}.", ci->Name, ci->LCID);

    // Display the result using ja-JP Compare of coté < côte.
    Console::WriteLine("ja-JP Compare: {0} {2} {1}",
        s2, s3, sign[ci->Compare(s2, s3) + 1]);
}

// This code produces the following output.
//
// The LCID for fr-FR is 1036.
// fr-FR Compare: Coté = coté
// fr-FR Compare: coté > côte
// The LCID for ja-JP is 1041.
// ja-JP Compare: coté < côte

Inheritance Hierarchy

System..::.Object
System.Globalization..::.CompareInfo

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.

Platforms

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.

Version Information

.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

Reference

CompareInfo Members

System.Globalization Namespace