String.ToUpperInvariant String.ToUpperInvariant String.ToUpperInvariant String.ToUpperInvariant Method

Definition

Namespace:
System System System System
Assemblies:
System.Runtime.dll, mscorlib.dll, netstandard.dll

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

public:
 System::String ^ ToUpperInvariant();
[System.Runtime.TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
public string ToUpperInvariant ();
member this.ToUpperInvariant : unit -> string
Public Function ToUpperInvariant () As String
Returns
String String String 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

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.

Security Considerations

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.

Applies to

See Also