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StringComparer.OrdinalIgnoreCase Property

Updated: August 2010

Gets a StringComparer object that performs a case-insensitive ordinal string comparison.

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

'Declaration
Public Shared ReadOnly Property OrdinalIgnoreCase As StringComparer
'Usage
Dim value As StringComparer 

value = StringComparer.OrdinalIgnoreCase

Property Value

Type: System.StringComparer
A StringComparer object.

The StringComparer returned by the OrdinalIgnoreCase property treats the characters in the strings to compare as if they were converted to uppercase using the conventions of the invariant culture, and then performs a simple byte comparison that is independent of language. This is most appropriate when comparing strings that are generated programmatically or when comparing case-insensitive resources such as paths and filenames.

The OrdinalIgnoreCase property actually returns an instance of an anonymous class derived from the StringComparer class.

The following code example demonstrates the properties and the Create method of the StringComparer class. The example illustrates how different StringComparer objects sort three versions of the Latin letter I.

' This code example demonstrates members of the System.StringComparer class. 

Imports System
Imports System.Collections
Imports System.Collections.Generic
Imports System.Globalization
Imports System.Threading

Class Sample

    Public Shared Sub Main() 
        ' Create a list of string. 
        Dim list As New List(Of String) 

        ' Get the tr-TR (Turkish-Turkey) culture. 
        Dim turkish As New CultureInfo("tr-TR")

        ' Get the culture that is associated with the current thread. 
        Dim thisCulture As CultureInfo = Thread.CurrentThread.CurrentCulture

        ' Get the standard StringComparers. 
        Dim invCmp As StringComparer = StringComparer.InvariantCulture
        Dim invICCmp As StringComparer = StringComparer.InvariantCultureIgnoreCase
        Dim currCmp As StringComparer = StringComparer.CurrentCulture
        Dim currICCmp As StringComparer = StringComparer.CurrentCultureIgnoreCase
        Dim ordCmp As StringComparer = StringComparer.Ordinal
        Dim ordICCmp As StringComparer = StringComparer.OrdinalIgnoreCase

        ' Create a StringComparer that uses the Turkish culture and ignores case. 
        Dim turkICComp As StringComparer = StringComparer.Create(turkish, True)

        ' Define three strings consisting of different versions of the letter I. 
        ' LATIN CAPITAL LETTER I (U+0049) 
        Dim capitalLetterI As String = "I" 

        ' LATIN SMALL LETTER I (U+0069) 
        Dim smallLetterI As String = "i" 

        ' LATIN SMALL LETTER DOTLESS I (U+0131) 
        Dim smallLetterDotlessI As String = "ı" 

        ' Add the three strings to the list.
        list.Add(capitalLetterI)
        list.Add(smallLetterI)
        list.Add(smallLetterDotlessI)

        ' Display the original list order.
        Display(list, "The original order of the list entries...")

        ' Sort the list using the invariant culture.
        list.Sort(invCmp)
        Display(list, "Invariant culture...")
        list.Sort(invICCmp)
        Display(list, "Invariant culture, ignore case...")

        ' Sort the list using the current culture.
        Console.WriteLine("The current culture is ""{0}"".", thisCulture.Name)
        list.Sort(currCmp)
        Display(list, "Current culture...")
        list.Sort(currICCmp)
        Display(list, "Current culture, ignore case...")

        ' Sort the list using the ordinal value of the character code points.
        list.Sort(ordCmp)
        Display(list, "Ordinal...")
        list.Sort(ordICCmp)
        Display(list, "Ordinal, ignore case...")

        ' Sort the list using the Turkish culture, which treats LATIN SMALL LETTER  
        ' DOTLESS I differently than LATIN SMALL LETTER I.
        list.Sort(turkICComp)
        Display(list, "Turkish culture, ignore case...")

    End Sub 'Main

    Public Shared Sub Display(ByVal lst As List(Of String), ByVal title As String)
        Dim c As Char 
        Dim s As String 
        Dim codePoint As Integer

        Console.WriteLine(title)
        For Each s In lst
            c = s(0)
            codePoint = Convert.ToInt32(c)
            Console.WriteLine("0x{0:x}", codePoint)
        Next s
        Console.WriteLine()
    End Sub 'Display
End Class 'Sample '

'This code example produces the following results: 

'The original order of the list entries... 
'0x49 
'0x69 
'0x131 

'Invariant culture... 
'0x69 
'0x49 
'0x131 

'Invariant culture, ignore case... 
'0x49 
'0x69 
'0x131 

'The current culture is "en-US". 
'Current culture... 
'0x69 
'0x49 
'0x131 

'Current culture, ignore case... 
'0x49 
'0x69 
'0x131 

'Ordinal... 
'0x49 
'0x69 
'0x131 

'Ordinal, ignore case... 
'0x69 
'0x49 
'0x131 

'Turkish culture, ignore case... 
'0x131 
'0x49 
'0x69 
'

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

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

August 2010

Noted that casing uses the conventions of the invariant culture.

Customer feedback.

May 2010

Added usage guidelines.

Customer feedback.

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