System.Globalization.TextElementEnumerator Class

Enumerates the text elements of a string.

See Also: TextElementEnumerator Members


public class TextElementEnumerator : IEnumerator


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 tp:// 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.

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.

When an enumerator is created, it takes a snapshot of the current state of the string. Two enumerators created from the same string at the same time can have different snapshots of 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 TextElementEnumerator.Current throws an exception.

Initially, the enumerator is positioned before the first text element in the string. TextElementEnumerator.Reset also brings the enumerator back to this position. Therefore, after an enumerator is created or after a TextElementEnumerator.Reset is called, TextElementEnumerator.MoveNext must be called to advance the enumerator to the first text element of the string before reading the value of TextElementEnumerator.Current.

TextElementEnumerator.Current returns the same object until either TextElementEnumerator.MoveNext or TextElementEnumerator.Reset is called.

After the end of the string is passed, the enumerator is again in an invalid state and calling TextElementEnumerator.MoveNext returns false. Calling TextElementEnumerator.Current throws an exception if the last call to TextElementEnumerator.MoveNext returned false.


Namespace: System.Globalization
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0,,