HybridDictionary.GetEnumerator Method
Returns an IDictionaryEnumerator that can iterate through the HybridDictionary.
[Visual Basic] Public Overridable Function GetEnumerator() As IDictionaryEnumerator _ Implements IDictionary.GetEnumerator [C#] public virtual IDictionaryEnumerator GetEnumerator(); [C++] public: virtual IDictionaryEnumerator* GetEnumerator(); [JScript] public function GetEnumerator() : IDictionaryEnumerator;
Return Value
An IDictionaryEnumerator for the HybridDictionary.
Implements
Remarks
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. Reset also brings the enumerator back to this position. At this position, calling Current throws an exception. Therefore, you must call MoveNext to advance the enumerator to the first element of the collection before reading the value of Current.
Current returns the same object until either MoveNext or Reset is called. MoveNext sets 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 MoveNext returns false. If the last call to MoveNext returned false, calling Current throws an exception. To set Current to the first element of the collection again, you can call Reset followed by 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 MoveNext or Reset throws an InvalidOperationException. If the collection is modified between MoveNext and Current, 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.
Example
[Visual Basic, C#, C++] The following code example enumerates the elements of a HybridDictionary.
[Visual Basic] Imports System Imports System.Collections Imports System.Collections.Specialized Public Class SamplesHybridDictionary Public Shared Sub Main() ' Creates and initializes a new HybridDictionary. Dim myCol As New HybridDictionary() myCol.Add("Braeburn Apples", "1.49") myCol.Add("Fuji Apples", "1.29") myCol.Add("Gala Apples", "1.49") myCol.Add("Golden Delicious Apples", "1.29") myCol.Add("Granny Smith Apples", "0.89") myCol.Add("Red Delicious Apples", "0.99") myCol.Add("Plantain Bananas", "1.49") myCol.Add("Yellow Bananas", "0.79") myCol.Add("Strawberries", "3.33") myCol.Add("Cranberries", "5.98") myCol.Add("Navel Oranges", "1.29") myCol.Add("Grapes", "1.99") myCol.Add("Honeydew Melon", "0.59") myCol.Add("Seedless Watermelon", "0.49") myCol.Add("Pineapple", "1.49") myCol.Add("Nectarine", "1.99") myCol.Add("Plums", "1.69") myCol.Add("Peaches", "1.99") ' Displays the values in the HybridDictionary in three different ways. Console.WriteLine("Displays the elements using for each:") PrintKeysAndValues(myCol) Console.WriteLine("Displays the elements using the IDictionaryEnumerator:") PrintKeysAndValues2(myCol) Console.WriteLine("Displays the elements using the Keys, Values, Count, and indexer properties:") PrintKeysAndValues3(myCol) End Sub 'Main Public Shared Sub PrintKeysAndValues(myCol As IDictionary) Console.WriteLine(" KEY VALUE") Dim de As DictionaryEntry For Each de In myCol Console.WriteLine(" {0,-25} {1}", de.Key, de.Value) Next de Console.WriteLine() End Sub 'PrintKeysAndValues Public Shared Sub PrintKeysAndValues2(myCol As IDictionary) Dim myEnumerator As IDictionaryEnumerator = myCol.GetEnumerator() Console.WriteLine(" KEY VALUE") While myEnumerator.MoveNext() Console.WriteLine(" {0,-25} {1}", myEnumerator.Key, myEnumerator.Value) End While Console.WriteLine() End Sub 'PrintKeysAndValues2 Public Shared Sub PrintKeysAndValues3(myCol As HybridDictionary) Dim myKeys(myCol.Count) As [String] myCol.Keys.CopyTo(myKeys, 0) Console.WriteLine(" INDEX KEY VALUE") Dim i As Integer For i = 0 To myCol.Count - 1 Console.WriteLine(" {0,-5} {1,-25} {2}", i, myKeys(i), myCol(myKeys(i))) Next i Console.WriteLine() End Sub 'PrintKeysAndValues3 End Class 'SamplesHybridDictionary 'This code produces the following output. ' 'Displays the elements using for each: ' KEY VALUE ' Seedless Watermelon 0.49 ' Nectarine 1.99 ' Cranberries 5.98 ' Plantain Bananas 1.49 ' Honeydew Melon 0.59 ' Pineapple 1.49 ' Strawberries 3.33 ' Grapes 1.99 ' Braeburn Apples 1.49 ' Peaches 1.99 ' Red Delicious Apples 0.99 ' Golden Delicious Apples 1.29 ' Yellow Bananas 0.79 ' Granny Smith Apples 0.89 ' Gala Apples 1.49 ' Plums 1.69 ' Navel Oranges 1.29 ' Fuji Apples 1.29 ' 'Displays the elements using the IDictionaryEnumerator: ' KEY VALUE ' Seedless Watermelon 0.49 ' Nectarine 1.99 ' Cranberries 5.98 ' Plantain Bananas 1.49 ' Honeydew Melon 0.59 ' Pineapple 1.49 ' Strawberries 3.33 ' Grapes 1.99 ' Braeburn Apples 1.49 ' Peaches 1.99 ' Red Delicious Apples 0.99 ' Golden Delicious Apples 1.29 ' Yellow Bananas 0.79 ' Granny Smith Apples 0.89 ' Gala Apples 1.49 ' Plums 1.69 ' Navel Oranges 1.29 ' Fuji Apples 1.29 ' 'Displays the elements using the Keys, Values, Count, and indexer properties: ' INDEX KEY VALUE ' 0 Seedless Watermelon 0.49 ' 1 Nectarine 1.99 ' 2 Cranberries 5.98 ' 3 Plantain Bananas 1.49 ' 4 Honeydew Melon 0.59 ' 5 Pineapple 1.49 ' 6 Strawberries 3.33 ' 7 Grapes 1.99 ' 8 Braeburn Apples 1.49 ' 9 Peaches 1.99 ' 10 Red Delicious Apples 0.99 ' 11 Golden Delicious Apples 1.29 ' 12 Yellow Bananas 0.79 ' 13 Granny Smith Apples 0.89 ' 14 Gala Apples 1.49 ' 15 Plums 1.69 ' 16 Navel Oranges 1.29 ' 17 Fuji Apples 1.29 [C#] using System; using System.Collections; using System.Collections.Specialized; public class SamplesHybridDictionary { public static void Main() { // Creates and initializes a new HybridDictionary. HybridDictionary myCol = new HybridDictionary(); myCol.Add( "Braeburn Apples", "1.49" ); myCol.Add( "Fuji Apples", "1.29" ); myCol.Add( "Gala Apples", "1.49" ); myCol.Add( "Golden Delicious Apples", "1.29" ); myCol.Add( "Granny Smith Apples", "0.89" ); myCol.Add( "Red Delicious Apples", "0.99" ); myCol.Add( "Plantain Bananas", "1.49" ); myCol.Add( "Yellow Bananas", "0.79" ); myCol.Add( "Strawberries", "3.33" ); myCol.Add( "Cranberries", "5.98" ); myCol.Add( "Navel Oranges", "1.29" ); myCol.Add( "Grapes", "1.99" ); myCol.Add( "Honeydew Melon", "0.59" ); myCol.Add( "Seedless Watermelon", "0.49" ); myCol.Add( "Pineapple", "1.49" ); myCol.Add( "Nectarine", "1.99" ); myCol.Add( "Plums", "1.69" ); myCol.Add( "Peaches", "1.99" ); // Displays the values in the HybridDictionary in three different ways. Console.WriteLine( "Displays the elements using foreach:" ); PrintKeysAndValues( myCol ); Console.WriteLine( "Displays the elements using the IDictionaryEnumerator:" ); PrintKeysAndValues2( myCol ); Console.WriteLine( "Displays the elements using the Keys, Values, Count, and indexer properties:" ); PrintKeysAndValues3( myCol ); } public static void PrintKeysAndValues( IDictionary myCol ) { Console.WriteLine( " KEY VALUE" ); foreach ( DictionaryEntry de in myCol ) Console.WriteLine( " {0,-25} {1}", de.Key, de.Value ); Console.WriteLine(); } public static void PrintKeysAndValues2( IDictionary myCol ) { IDictionaryEnumerator myEnumerator = myCol.GetEnumerator(); Console.WriteLine( " KEY VALUE" ); while ( myEnumerator.MoveNext() ) Console.WriteLine( " {0,-25} {1}", myEnumerator.Key, myEnumerator.Value ); Console.WriteLine(); } public static void PrintKeysAndValues3( HybridDictionary myCol ) { String[] myKeys = new String[myCol.Count]; myCol.Keys.CopyTo( myKeys, 0 ); Console.WriteLine( " INDEX KEY VALUE" ); for ( int i = 0; i < myCol.Count; i++ ) Console.WriteLine( " {0,-5} {1,-25} {2}", i, myKeys[i], myCol[myKeys[i]] ); Console.WriteLine(); } } /* This code produces the following output. Displays the elements using foreach: KEY VALUE Seedless Watermelon 0.49 Nectarine 1.99 Cranberries 5.98 Plantain Bananas 1.49 Honeydew Melon 0.59 Pineapple 1.49 Strawberries 3.33 Grapes 1.99 Braeburn Apples 1.49 Peaches 1.99 Red Delicious Apples 0.99 Golden Delicious Apples 1.29 Yellow Bananas 0.79 Granny Smith Apples 0.89 Gala Apples 1.49 Plums 1.69 Navel Oranges 1.29 Fuji Apples 1.29 Displays the elements using the IDictionaryEnumerator: KEY VALUE Seedless Watermelon 0.49 Nectarine 1.99 Cranberries 5.98 Plantain Bananas 1.49 Honeydew Melon 0.59 Pineapple 1.49 Strawberries 3.33 Grapes 1.99 Braeburn Apples 1.49 Peaches 1.99 Red Delicious Apples 0.99 Golden Delicious Apples 1.29 Yellow Bananas 0.79 Granny Smith Apples 0.89 Gala Apples 1.49 Plums 1.69 Navel Oranges 1.29 Fuji Apples 1.29 Displays the elements using the Keys, Values, Count, and indexer properties: INDEX KEY VALUE 0 Seedless Watermelon 0.49 1 Nectarine 1.99 2 Cranberries 5.98 3 Plantain Bananas 1.49 4 Honeydew Melon 0.59 5 Pineapple 1.49 6 Strawberries 3.33 7 Grapes 1.99 8 Braeburn Apples 1.49 9 Peaches 1.99 10 Red Delicious Apples 0.99 11 Golden Delicious Apples 1.29 12 Yellow Bananas 0.79 13 Granny Smith Apples 0.89 14 Gala Apples 1.49 15 Plums 1.69 16 Navel Oranges 1.29 17 Fuji Apples 1.29 */ [C++] #using <mscorlib.dll> #using <System.dll> using namespace System; using namespace System::Collections; using namespace System::Collections::Specialized; void PrintKeysAndValues( IDictionary* myCol ) { Console::WriteLine( S" KEY VALUE" ); IEnumerator* myEnum = myCol->GetEnumerator(); while (myEnum->MoveNext()) { DictionaryEntry de = *__try_cast<DictionaryEntry*>(myEnum->Current); Console::WriteLine( S" {0,-25} {1}", de.Key, de.Value ); } Console::WriteLine(); } void PrintKeysAndValues2( IDictionary* myCol ) { IDictionaryEnumerator* myEnumerator = myCol->GetEnumerator(); Console::WriteLine( S" KEY VALUE" ); while ( myEnumerator->MoveNext() ) Console::WriteLine( S" {0,-25} {1}", myEnumerator->Key, myEnumerator->Value ); Console::WriteLine(); } void PrintKeysAndValues3( HybridDictionary* myCol ) { String* myKeys[] = new String*[myCol->Count]; myCol->Keys->CopyTo( myKeys, 0 ); Console::WriteLine( S" INDEX KEY VALUE" ); for ( int i = 0; i < myCol->Count; i++ ) Console::WriteLine( S" {0,-5} {1,-25} {2}", __box(i), myKeys->Item[i], myCol->Item[myKeys[i]] ); Console::WriteLine(); } int main() { // Creates and initializes a new HybridDictionary. HybridDictionary* myCol = new HybridDictionary(); myCol->Add( S"Braeburn Apples", S"1.49" ); myCol->Add( S"Fuji Apples", S"1.29" ); myCol->Add( S"Gala Apples", S"1.49" ); myCol->Add( S"Golden Delicious Apples", S"1.29" ); myCol->Add( S"Granny Smith Apples", S"0.89" ); myCol->Add( S"Red Delicious Apples", S"0.99" ); myCol->Add( S"Plantain Bananas", S"1.49" ); myCol->Add( S"Yellow Bananas", S"0.79" ); myCol->Add( S"Strawberries", S"3.33" ); myCol->Add( S"Cranberries", S"5.98" ); myCol->Add( S"Navel Oranges", S"1.29" ); myCol->Add( S"Grapes", S"1.99" ); myCol->Add( S"Honeydew Melon", S"0.59" ); myCol->Add( S"Seedless Watermelon", S"0.49" ); myCol->Add( S"Pineapple", S"1.49" ); myCol->Add( S"Nectarine", S"1.99" ); myCol->Add( S"Plums", S"1.69" ); myCol->Add( S"Peaches", S"1.99" ); // Displays the values in the HybridDictionary in three different ways. Console::WriteLine( S"Displays the elements using foreach:" ); PrintKeysAndValues( myCol ); Console::WriteLine( S"Displays the elements using the IDictionaryEnumerator:" ); PrintKeysAndValues2( myCol ); Console::WriteLine( S"Displays the elements using the Keys, Values, Count, and indexer properties:" ); PrintKeysAndValues3( myCol ); } /* This code produces the following output. Displays the elements using foreach: KEY VALUE Seedless Watermelon 0.49 Nectarine 1.99 Cranberries 5.98 Plantain Bananas 1.49 Honeydew Melon 0.59 Pineapple 1.49 Strawberries 3.33 Grapes 1.99 Braeburn Apples 1.49 Peaches 1.99 Red Delicious Apples 0.99 Golden Delicious Apples 1.29 Yellow Bananas 0.79 Granny Smith Apples 0.89 Gala Apples 1.49 Plums 1.69 Navel Oranges 1.29 Fuji Apples 1.29 Displays the elements using the IDictionaryEnumerator: KEY VALUE Seedless Watermelon 0.49 Nectarine 1.99 Cranberries 5.98 Plantain Bananas 1.49 Honeydew Melon 0.59 Pineapple 1.49 Strawberries 3.33 Grapes 1.99 Braeburn Apples 1.49 Peaches 1.99 Red Delicious Apples 0.99 Golden Delicious Apples 1.29 Yellow Bananas 0.79 Granny Smith Apples 0.89 Gala Apples 1.49 Plums 1.69 Navel Oranges 1.29 Fuji Apples 1.29 Displays the elements using the Keys, Values, Count, and indexer properties: INDEX KEY VALUE 0 Seedless Watermelon 0.49 1 Nectarine 1.99 2 Cranberries 5.98 3 Plantain Bananas 1.49 4 Honeydew Melon 0.59 5 Pineapple 1.49 6 Strawberries 3.33 7 Grapes 1.99 8 Braeburn Apples 1.49 9 Peaches 1.99 10 Red Delicious Apples 0.99 11 Golden Delicious Apples 1.29 12 Yellow Bananas 0.79 13 Granny Smith Apples 0.89 14 Gala Apples 1.49 15 Plums 1.69 16 Navel Oranges 1.29 17 Fuji Apples 1.29 */
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Requirements
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework
See Also
HybridDictionary Class | HybridDictionary Members | System.Collections.Specialized Namespace | IDictionaryEnumerator | IEnumerator