StringComparer.OrdinalIgnoreCase Property

Reference

Definition

Namespace:: System

Assembly:: System.Runtime.Extensions.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: StringComparer.cs

Source:: StringComparer.cs

Source:: StringComparer.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

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

public:
 static property StringComparer ^ OrdinalIgnoreCase { StringComparer ^ get(); };

public static StringComparer OrdinalIgnoreCase { get; }

static member OrdinalIgnoreCase : StringComparer

Public Shared ReadOnly Property OrdinalIgnoreCase As StringComparer

Property Value

StringComparer

A StringComparer object.

Examples

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 example demonstrates members of the
// System::StringComparer class.

using namespace System;
using namespace System::Collections;
using namespace System::Collections::Generic;
using namespace System::Globalization;
using namespace System::Threading;

void Display(List<String^>^ stringList, String^ title)
{
    Char firstChar;
    int codePoint;
    Console::WriteLine(title);
    for each (String^ s in stringList)
    {
        firstChar = s[0];
        codePoint = Convert::ToInt32(firstChar);
        Console::WriteLine("0x{0:x}", codePoint);
    }
    Console::WriteLine();
}

int main()
{
    // Create a list of string.
    List<String^>^ stringList = gcnew List<String^>();

    // Get the tr-TR (Turkish-Turkey) culture.
    CultureInfo^ turkishCulture = gcnew CultureInfo("tr-TR");

    // Get the culture that is associated with the current thread.
    CultureInfo^ currentCulture = Thread::CurrentThread->CurrentCulture;

    // Get the standard StringComparers.
    StringComparer^ invariant = StringComparer::InvariantCulture;
    StringComparer^ invariantIgnoreCase =
        StringComparer::InvariantCultureIgnoreCase;
    StringComparer^ current = StringComparer::CurrentCulture;
    StringComparer^ currentIgnoreCase =
        StringComparer::CurrentCultureIgnoreCase;
    StringComparer^ ordinal = StringComparer::Ordinal;
    StringComparer^ ordinalIgnoreCase = StringComparer::OrdinalIgnoreCase;

    // Create a StringComparer that uses the Turkish culture and ignores
    // case.
    StringComparer^ turkishIgnoreCase =
        StringComparer::Create(turkishCulture, true);

    // Define three strings consisting of different versions of the
    // letter I. LATIN CAPITAL LETTER I (U+0049)
    String^ capitalLetterI = "I";

    // LATIN SMALL LETTER I (U+0069)
    String^ smallLetterI = "i";

    // LATIN SMALL LETTER DOTLESS I (U+0131)
    String^ smallLetterDotlessI = L"\u0131";

    // Add the three strings to the list.
    stringList->Add(capitalLetterI);
    stringList->Add(smallLetterI);
    stringList->Add(smallLetterDotlessI);

    // Display the original list order.
    Display(stringList, "The original order of the list entries...");

    // Sort the list using the invariant culture.
    stringList->Sort(invariant);
    Display(stringList, "Invariant culture...");
    stringList->Sort(invariantIgnoreCase);
    Display(stringList, "Invariant culture, ignore case...");

    // Sort the list using the current culture.
    Console::WriteLine("The current culture is \"{0}\".",
        currentCulture->Name);
    stringList->Sort(current);
    Display(stringList, "Current culture...");
    stringList->Sort(currentIgnoreCase);
    Display(stringList, "Current culture, ignore case...");

    // Sort the list using the ordinal value of the character code points.
    stringList->Sort(ordinal);
    Display(stringList, "Ordinal...");
    stringList->Sort(ordinalIgnoreCase);
    Display(stringList, "Ordinal, ignore case...");

    // Sort the list using the Turkish culture, which treats LATIN SMALL
    // LETTER DOTLESS I differently than LATIN SMALL LETTER I.
    stringList->Sort(turkishIgnoreCase);
    Display(stringList, "Turkish culture, ignore case...");
}
/*
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

*/

// This example demonstrates members of the 
// System.StringComparer class.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.Threading;

class Sample 
{
    public static void Main() 
    {
        // Create a list of string.
        List<string> list = new List<string>();

        // Get the tr-TR (Turkish-Turkey) culture.
        CultureInfo turkish = new CultureInfo("tr-TR");

        // Get the culture that is associated with the current thread.
        CultureInfo thisCulture = Thread.CurrentThread.CurrentCulture;

        // Get the standard StringComparers.
        StringComparer invCmp =   StringComparer.InvariantCulture;
        StringComparer invICCmp = StringComparer.InvariantCultureIgnoreCase;
        StringComparer currCmp = StringComparer.CurrentCulture;
        StringComparer currICCmp = StringComparer.CurrentCultureIgnoreCase;
        StringComparer ordCmp = StringComparer.Ordinal;
        StringComparer ordICCmp = StringComparer.OrdinalIgnoreCase;

        // Create a StringComparer that uses the Turkish culture and ignores case.
        StringComparer turkICComp = StringComparer.Create(turkish, true);

        // Define three strings consisting of different versions of the letter I.
        // LATIN CAPITAL LETTER I (U+0049)
        string capitalLetterI = "I";  

        // LATIN SMALL LETTER I (U+0069)
        string smallLetterI   = "i";

        // LATIN SMALL LETTER DOTLESS I (U+0131)
        string smallLetterDotlessI = "\u0131";

        // 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...");
    }

    public static void Display(List<string> lst, string title)
    {
        Char c;
        int  codePoint;
        Console.WriteLine(title);
        foreach (string s in lst)
        {
            c = s[0];
            codePoint = Convert.ToInt32(c);
            Console.WriteLine("0x{0:x}", codePoint); 
        }
        Console.WriteLine();
    }
}
/*
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

*/

// This example demonstrates members of the 
// System.StringComparer class.

open System
open System.Globalization
open System.Threading

let display (lst: ResizeArray<string>) title =
    printfn $"%s{title}"
    for s in lst do
        let c = s[0]
        let codePoint = Convert.ToInt32 c
        printfn $"0x{codePoint:x}"
    printfn ""

// Create a list of string.
let list = ResizeArray()

// Get the tr-TR (Turkish-Turkey) culture.
let turkish = CultureInfo "tr-TR"

// Get the culture that is associated with the current thread.
let thisCulture = Thread.CurrentThread.CurrentCulture

// Get the standard StringComparers.
let invCmp =   StringComparer.InvariantCulture
let invICCmp = StringComparer.InvariantCultureIgnoreCase
let currCmp = StringComparer.CurrentCulture
let currICCmp = StringComparer.CurrentCultureIgnoreCase
let ordCmp = StringComparer.Ordinal
let ordICCmp = StringComparer.OrdinalIgnoreCase

// Create a StringComparer that uses the Turkish culture and ignores case.
let turkICComp = StringComparer.Create(turkish, true)

// Define three strings consisting of different versions of the letter I.
// LATIN CAPITAL LETTER I (U+0049)
let capitalLetterI = "I"  

// LATIN SMALL LETTER I (U+0069)
let smallLetterI   = "i"

// LATIN SMALL LETTER DOTLESS I (U+0131)
let smallLetterDotlessI = "\u0131"

// 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.
printfn $"The current culture is \"{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..."


(*
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

*)

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

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
    
    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
End Class

'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
'

Remarks

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.

Applies to

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