Articolo
11/17/2011

StringInfo.GetTextElementEnumerator Method (String, Int32)

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Updated: December 2010

Returns an enumerator that iterates through the text elements of the string, starting at the specified index.

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

Syntax

'Declaration
Public Shared Function GetTextElementEnumerator ( _
    str As String, _
    index As Integer _
) As TextElementEnumerator

public static TextElementEnumerator GetTextElementEnumerator(
    string str,
    int index
)

Parameters

str
Type: System.String
The string to iterate through.

index
Type: System.Int32
The zero-based index at which to start iterating.

Return Value

Type: System.Globalization.TextElementEnumerator
A TextElementEnumerator for the string starting at index.

Exceptions

Exception	Condition
ArgumentNullException	str is nulla null reference (Nothing in Visual Basic).
ArgumentOutOfRangeException	index is outside the range of valid indexes for str.

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.

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.

Change History

Date	History	Reason
December 2010	Removed information about operations that cause the enumerator to throw an InvalidOperationException.	Customer feedback.

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