String.ToUpperInvariant Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

String.Manipulation.cs

Returns a copy of this String object converted to uppercase using the casing rules of the invariant culture.

public:
 System::String ^ ToUpperInvariant();

public string ToUpperInvariant ();

member this.ToUpperInvariant : unit -> string

Public Function ToUpperInvariant () As String

Returns

String

The uppercase equivalent of the current string.

Examples

The following example defines a string array that contains a single word in a number of languages. The ToUpperInvariant method is used to populate the elements of a parallel array with the case-insensitive version of each word. The Array.Sort<TKey,TValue>(TKey[], TValue[], IComparer<TKey>) method is used to sort the case-sensitive array based on the order of elements in the uppercase array to ensure that elements appear in the same order regardless of language.

using System;
using System.IO;

public class Example
{
   public static void Main()
   {
      string[] words = { "Tuesday", "Salı", "Вторник", "Mardi", 
                         "Τρίτη", "Martes", "יום שלישי", 
                         "الثلاثاء", "วันอังคาร" };
      StreamWriter sw = new StreamWriter(@".\output.txt");
            
      // Display array in unsorted order.
      foreach (string word in words)
         sw.WriteLine(word);

      sw.WriteLine();

      // Create parallel array of words by calling ToUpperInvariant.
      string[] upperWords = new string[words.Length];
      for (int ctr = words.GetLowerBound(0); ctr <= words.GetUpperBound(0); ctr++)
         upperWords[ctr] = words[ctr].ToUpperInvariant();
      
      // Sort the words array based on the order of upperWords.
      Array.Sort(upperWords, words, StringComparer.InvariantCulture);
      
      // Display the sorted array.
      foreach (string word in words)
         sw.WriteLine(word);

      sw.Close();      
   }
}
// The example produces the following output:
//       Tuesday
//       Salı
//       Вторник
//       Mardi
//       Τρίτη
//       Martes
//       יום שלישי
//       الثلاثاء
//       วันอังคาร
//       
//       Mardi
//       Martes
//       Salı
//       Tuesday
//       Τρίτη
//       Вторник
//       יום שלישי
//       الثلاثاء
//       วันอังคาร

open System
open System.IO

do
    let words = 
        [| "Tuesday"; "Salı"; "Вторник"; "Mardi" 
           "Τρίτη"; "Martes"; "יום שלישי" 
           "الثلاثاء"; "วันอังคาร" |]
    use sw = new StreamWriter(@".\output.txt")
        
    // Display array in unsorted order.
    for word in words do
        sw.WriteLine word

    sw.WriteLine()

    // Create parallel array of words by calling ToUpperInvariant.
    let upperWords = words |> Array.map (fun x -> x.ToUpperInvariant())
    
    // Sort the words array based on the order of upperWords.
    Array.Sort(upperWords, words, StringComparer.InvariantCulture)
    
    // Display the sorted array.
    for word in words do
        sw.WriteLine word
    sw.Close()      
// The example produces the following output:
//       Tuesday
//       Salı
//       Вторник
//       Mardi
//       Τρίτη
//       Martes
//       יום שלישי
//       الثلاثاء
//       วันอังคาร
//       
//       Mardi
//       Martes
//       Salı
//       Tuesday
//       Τρίτη
//       Вторник
//       יום שלישי
//       الثلاثاء
//       วันอังคาร

Imports System.IO

Module Example
   Public Sub Main()
      Dim words() As String = { "Tuesday", "Salı", "Вторник", "Mardi", _
                                "Τρίτη", "Martes", "יום שלישי", _
                                "الثلاثاء", "วันอังคาร" }
      Dim sw As New StreamWriter(".\output.txt")
      
      ' Display array in unsorted order.
      For Each word As String In words
         sw.WriteLine(word)
      Next
      sw.WriteLine()

      ' Create parallel array of words by calling ToUpperInvariant.
      Dim upperWords(words.Length - 1) As String
      For ctr As Integer = words.GetLowerBound(0) To words.GetUpperBound(0)
         upperWords(ctr) = words(ctr).ToUpperInvariant()
      Next
      
      ' Sort the words array based on the order of upperWords.
      Array.Sort(upperWords, words, StringComparer.InvariantCulture)
      
      ' Display the sorted array.
      For Each word As String In words
         sw.WriteLine(word)
      Next
      
      sw.Close()
   End Sub
End Module
' The example produces the following output:
'       Tuesday
'       Salı
'       Вторник
'       Mardi
'       Τρίτη
'       Martes
'       יום שלישי
'       الثلاثاء
'       วันอังคาร
'       
'       Mardi
'       Martes
'       Salı
'       Tuesday
'       Τρίτη
'       Вторник
'       יום שלישי
'       الثلاثاء
'       วันอังคาร

Remarks

The invariant culture represents a culture that is culture-insensitive. It is associated with the English language but not with a specific country or region. For more information, see the CultureInfo.InvariantCulture property.

If your application depends on the case of a string changing in a predictable way that is unaffected by the current culture, use the ToUpperInvariant method. The ToUpperInvariant method is equivalent to ToUpper(CultureInfo.InvariantCulture). The method is recommended when a collection of strings must appear in a predictable order in a user interface control.

Note

This method does not modify the value of the current instance. Instead, it returns a new string in which all characters in the current instance are converted to uppercase.

If you need the lowercase or uppercase version of an operating system identifier, such as a file name, named pipe, or registry key, use the ToLowerInvariant or ToUpperInvariant methods.

See also

• ToLowerInvariant()
• ToUpper()
• InvariantCulture