StringInfo.GetTextElementEnumerator Method (String)
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Updated: December 2010
Returns an enumerator that iterates through the text elements of the entire string.
Namespace: System.Globalization
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Shared Function GetTextElementEnumerator ( _
str As String _
) As TextElementEnumerator
public static TextElementEnumerator GetTextElementEnumerator(
string str
)
Parameters
- str
Type: System.String
The string to iterate through.
Return Value
Type: System.Globalization.TextElementEnumerator
A TextElementEnumerator for the entire string.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | str is nulla null reference (Nothing in Visual Basic). |
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..
Text element enumerators are intended to be used only to read data in the string. Enumerators cannot be used to modify the underlying string.
The enumerator does not have exclusive access to the string.
The enumerator is in an invalid state if it is positioned before the first text element in the string or after the last text element in the string. Whenever the enumerator is in an invalid state, calling Current throws an exception.
Initially, the enumerator is positioned before the first text element in the string. Reset also brings the enumerator back to this position. Therefore, after an enumerator is created or after a Reset is called, MoveNext must be called to advance the enumerator to the first text element of the string before reading the value of Current.
Current returns the same object until either MoveNext or Reset is called.
After the end of the string is passed, the enumerator is again in an invalid state and calling MoveNext returns false. Calling Current throws an exception if the last call to MoveNext returned false.
Examples
The following code example demonstrates calling the GetTextElementEnumerator method. This code example is part of a larger example provided for the StringInfo class.
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.
See Also
Reference
Change History
Date |
History |
Reason |
|---|---|---|
December 2010 |
Removed information about operations that cause the enumerator to throw an InvalidOperationException. |
Customer feedback. |