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11/18/2011

StringInfo Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Provides functionality to split a string into text elements and to iterate through those text elements.

Inheritance Hierarchy

System.Object
System.Globalization.StringInfo

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

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public Class StringInfo

[ComVisibleAttribute(true)]
public class StringInfo

The StringInfo type exposes the following members.

Constructors

	Name	Description
	StringInfo()	Initializes a new instance of the StringInfo class.
	StringInfo(String)	Initializes a new instance of the StringInfo class to a specified string.

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Properties

	Name	Description
	LengthInTextElements	Gets the number of text elements in the current StringInfo object.
	String	Gets or sets the value of the current StringInfo object.

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Methods

	Name	Description
	Equals	Indicates whether the current StringInfo object is equal to a specified object. (Overrides Object.Equals(Object).)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Calculates a hash code for the value of the current StringInfo object. (Overrides Object.GetHashCode().)
	GetNextTextElement(String)	Gets the first text element in a specified string.
	GetNextTextElement(String, Int32)	Gets the text element at the specified index of the specified string.
	GetTextElementEnumerator(String)	Returns an enumerator that iterates through the text elements of the entire string.
	GetTextElementEnumerator(String, Int32)	Returns an enumerator that iterates through the text elements of the string, starting at the specified index.
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ParseCombiningCharacters	Returns the index of each base character, high surrogate, or control character within the specified string.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

The .NET Framework defines a text element as a unit of text that is displayed as a single character, that is, a grapheme. A text element can be a base character, a surrogate pair, or a combining character sequence. The Unicode Standard defines a surrogate pair as a coded character representation for a single abstract character that consists of a sequence of two code units, where the first unit of the pair is a high surrogate and the second is a low surrogate. The Unicode Standard defines a combining character sequence as a combination of a base character and one or more combining characters. A surrogate pair can represent a base character or a combining character.

For more information on surrogate pairs and combining character sequences, see The Unicode Standard at http://www.unicode.org.

Examples

This example shows how to use the GetTextElementEnumerator and ParseCombiningCharacters methods of the StringInfo class to manipulate a string that contains surrogate and combining characters.

Imports System.Globalization
Imports System.Text

Module Example
   Public Sub Demo(outputBlock As System.Windows.Controls.TextBlock)
      ' The string below contains combining characters.
      Dim chars() As Char = {"a"c, ChrW(&h0304), ChrW(&h0308), "b"c, "c"c, ChrW(&h0327)}
      Dim s As New String(chars)

      ' Show each 'character' in the string.
      EnumTextElements(outputBlock, s)

      ' Show the index in the string where each 'character' starts.
      EnumTextElementIndexes(outputBlock, s)
   End Sub

   ' Show how to enumerate each real character (honoring surrogates) in a string.
   Private Sub EnumTextElements(outputBlock As System.Windows.Controls.TextBlock, s As String)
      ' This StringBuilder holds the output results.
      Dim sb As New StringBuilder()

      ' Use the enumerator returned from GetTextElementEnumerator 
      ' method to examine each real character.
      Dim charEnum As TextElementEnumerator = StringInfo.GetTextElementEnumerator(s)
      Do While charEnum.MoveNext()
         sb.AppendFormat("Character at index {0} is '{1}'{2}", _
                         charEnum.ElementIndex, charEnum.GetTextElement(), vbCrLf)
      Loop

      ' Show the results.
      outputBlock.Text &= "Result of GetTextElementEnumerator:" & vbCrLf
      outputBlock.Text &= sb.ToString() & vbCrLf
   End Sub

   ' Show how to discover the index of each real character (honoring surrogates) in a string.
   Private Sub EnumTextElementIndexes(outputBlock As System.Windows.Controls.TextBlock, s As String)
      ' This StringBuilder holds the output results.
      Dim sb As New StringBuilder()

      ' Use the ParseCombiningCharacters method to 
      ' get the index of each real character in the string.
      Dim textElemIndex() As Integer = StringInfo.ParseCombiningCharacters(s)

      ' Iterate through each real character showing the character and the index where it was found.
      For i As Integer = 0 To textElemIndex.Length - 1
         sb.AppendFormat("Character {0} starts at index {1}{2}", _
                         i, textElemIndex(i), vbCrLf)
      Next

      ' Show the results.
      outputBlock.Text &= "Result of ParseCombiningCharacters:" & vbCrLf
      outputBlock.Text &= sb.ToString() & vbCrLf
   End Sub
End Module
' This code produces the following output.
'
' Result of GetTextElementEnumerator:
' Character at index 0 is 'a-"'
' Character at index 3 is 'b'
' Character at index 4 is 'c,'
' 
' Result of ParseCombiningCharacters:
' Character 0 starts at index 0
' Character 1 starts at index 3
' Character 2 starts at index 4

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

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // The string below contains combining characters.
      String s = "a\u0304\u0308bc\u0327";

      // Show each 'character' in the string.
      EnumTextElements(outputBlock, s);

      // Show the index in the string where each 'character' starts.
      EnumTextElementIndexes(outputBlock, s);
   }

   // Show how to enumerate each real character (honoring surrogates) in a string.
   static void EnumTextElements(System.Windows.Controls.TextBlock outputBlock, String s)
   {
      // This StringBuilder holds the output results.
      StringBuilder sb = new StringBuilder();

      // Use the enumerator returned from GetTextElementEnumerator 
      // method to examine each real character.
      TextElementEnumerator charEnum = StringInfo.GetTextElementEnumerator(s);
      while (charEnum.MoveNext())
      {
         sb.AppendFormat(
           "Character at index {0} is '{1}'\n",
           charEnum.ElementIndex, charEnum.GetTextElement());
      }

      // Show the results.
      outputBlock.Text += "Result of GetTextElementEnumerator:" + "\n";
      outputBlock.Text += sb + "\n";
   }

   // Show how to discover the index of each real character (honoring surrogates) in a string.
   static void EnumTextElementIndexes(System.Windows.Controls.TextBlock outputBlock, String s)
   {
      // This StringBuilder holds the output results.
      StringBuilder sb = new StringBuilder();

      // Use the ParseCombiningCharacters method to 
      // get the index of each real character in the string.
      Int32[] textElemIndex = StringInfo.ParseCombiningCharacters(s);

      // Iterate through each real character showing the character and the index where it was found.
      for (Int32 i = 0; i < textElemIndex.Length; i++)
      {
         sb.AppendFormat(
            "Character {0} starts at index {1}\n", i, textElemIndex[i]);
      }

      // Show the results.
      outputBlock.Text += "Result of ParseCombiningCharacters:" + "\n";
      outputBlock.Text += sb + "\n";
   }
}

// This code produces the following output.
//
// Result of GetTextElementEnumerator:
// Character at index 0 is 'a-"'
// Character at index 3 is 'b'
// Character at index 4 is 'c,'
// 
// Result of ParseCombiningCharacters:
// Character 0 starts at index 0
// Character 1 starts at index 3
// Character 2 starts at index 4

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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.

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