System.Collections.Specialized.StringEnumerator Class

Summary

Supports a simple iteration over a StringCollection.

C# Syntax:

public class StringEnumerator

Public static (non-instance) members of this type are safe for multithreaded operations. Instance members are not guaranteed to be thread-safe.

Enumerators only allow reading the data in the collection. Enumerators cannot be used to modify the underlying collection.

Initially, the enumerator is positioned before the first element in the collection. StringEnumerator.Reset also brings the enumerator back to this position. At this position, calling StringEnumerator.Current throws an exception. Therefore, you must call StringEnumerator.MoveNext to advance the enumerator to the first element of the collection before reading the value of StringEnumerator.Current.

StringEnumerator.Current returns the same object until either StringEnumerator.MoveNext or StringEnumerator.Reset is called. StringEnumerator.MoveNext sets StringEnumerator.Current to the next element.

After the end of the collection is passed, the enumerator is positioned after the last element in the collection, and calling StringEnumerator.MoveNext returns false. If the last call to StringEnumerator.MoveNext returned false, calling StringEnumerator.Current throws an exception. To set StringEnumerator.Current to the first element of the collection again, you can call StringEnumerator.Reset followed by StringEnumerator.MoveNext.

An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying or deleting elements, the enumerator is irrecoverably invalidated and the next call to StringEnumerator.MoveNext or StringEnumerator.Reset throws an InvalidOperationException. If the collection is modified between StringEnumerator.MoveNext and StringEnumerator.Current, StringEnumerator.Current will return the element that it is set to, even if the enumerator is already invalidated.

The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads could still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

System.Collections.Specialized Namespace | IEnumerable | IEnumerator | StringCollection

System.Collections.Specialized.StringEnumerator Member List:

Public Properties

Current

Read-only Gets the current element in the collection.

Public Methods

Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
MoveNext	Advances the enumerator to the next element of the collection.
Reset	Sets the enumerator to its initial position, which is before the first element in the collection.
ToString (inherited from System.Object)	See base class member description: System.Object.ToString Derived from System.Object, the primary base class for all objects.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Hierarchy:

• System.Object
• System.Collections.Specialized.StringEnumerator

System.Collections.Specialized.StringEnumerator Member Details

Summary

Gets the current element in the collection.

C# Syntax:

public string Current {get;}

Exceptions

Exception Type	Condition
InvalidOperationException	The enumerator is positioned before the first element of the collection or after the last element.

After an enumerator is created or after a StringEnumerator.Reset, StringEnumerator.MoveNext must be called to advance the enumerator to the first element of the collection before reading the value of StringEnumerator.Current; otherwise, StringEnumerator.Current is undefined.

StringEnumerator.Current also throws an exception if the last call to StringEnumerator.MoveNext returned false, which indicates the end of the collection.

StringEnumerator.Current does not move the position of the enumerator and consecutive calls to StringEnumerator.Current return the same object until either StringEnumerator.MoveNext or StringEnumerator.Reset is called.

An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying or deleting elements, the enumerator is irrecoverably invalidated and the next call to IEnumerator.MoveNext or IEnumerator.Reset throws an InvalidOperationException. If the collection is modified between IEnumerator.MoveNext and IEnumerator.Current, IEnumerator.Current will return the element that it is set to, even if the enumerator is already invalidated.

Return to top

Inherited
See base class member description: System.Object.Equals

C# Syntax:

public virtual bool Equals(    object obj );

For more information on members inherited from System.Object click on the link above.

Return to top

Inherited
See base class member description: System.Object.Finalize

C# Syntax:

~StringEnumerator();

For more information on members inherited from System.Object click on the link above.

Return to top

Inherited
See base class member description: System.Object.GetHashCode

C# Syntax:

public virtual int GetHashCode();

For more information on members inherited from System.Object click on the link above.

Return to top

Inherited
See base class member description: System.Object.GetType

C# Syntax:

public Type GetType();

For more information on members inherited from System.Object click on the link above.

Return to top

Inherited
See base class member description: System.Object.MemberwiseClone

C# Syntax:

protected object MemberwiseClone();

For more information on members inherited from System.Object click on the link above.

Return to top

Summary

Advances the enumerator to the next element of the collection.

C# Syntax:

public bool MoveNext();

Return Value:

true if the enumerator was successfully advanced to the next element; false if the enumerator has passed the end of the collection.

Exceptions

Exception Type	Condition
InvalidOperationException	The collection was modified after the enumerator was created.

After an enumerator is created or after a call to StringEnumerator.Reset, an enumerator is positioned before the first element of the collection, and the first call to StringEnumerator.MoveNext moves the enumerator over the first element of the collection.

After the end of the collection is passed, subsequent calls to StringEnumerator.MoveNext return false until StringEnumerator.Reset is called.

An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying or deleting elements, the enumerator is irrecoverably invalidated and the next call to IEnumerator.MoveNext or IEnumerator.Reset throws an InvalidOperationException. If the collection is modified between IEnumerator.MoveNext and IEnumerator.Current, IEnumerator.Current will return the element that it is set to, even if the enumerator is already invalidated.

Return to top

Summary

Sets the enumerator to its initial position, which is before the first element in the collection.

C# Syntax:

public void Reset();

Exceptions

Exception Type	Condition
InvalidOperationException	The collection was modified after the enumerator was created.

StringEnumerator.Reset moves the enumerator to the beginning of the collection, before the first element. After StringEnumerator.Reset, StringEnumerator.MoveNext must be called to advance the enumerator to the first element of the collection before reading the value of StringEnumerator.Current.

Return to top

Inherited
See base class member description: System.Object.ToString

C# Syntax:

public virtual string ToString();

For more information on members inherited from System.Object click on the link above.

Return to top

Top of page