NameObjectCollectionBase.BaseRemoveAt Method
Removes the entry at the specified index of the NameObjectCollectionBase instance.
[Visual Basic] Protected Sub BaseRemoveAt( _ ByVal index As Integer _ ) [C#] protected void BaseRemoveAt( int index ); [C++] protected: void BaseRemoveAt( int index ); [JScript] protected function BaseRemoveAt( index : int );
Parameters
- index
- The zero-based index of the entry to remove.
Exceptions
| Exception Type | Condition |
|---|---|
| ArgumentOutOfRangeException | index is outside the valid range of indexes for the collection. |
| NotSupportedException | The collection is read-only.
-or- The collection has a fixed size. |
Remarks
In collections of contiguous elements, such as lists, the elements that follow the removed element move up to occupy the vacated spot. If the collection is indexed, the indexes of the elements that are moved are also updated. This behavior does not apply to collections where elements are conceptually grouped into buckets, such as a hashtable.
Example
[Visual Basic, C#, C++] The following code example uses BaseRemove and BaseRemoveAt to remove elements from a NameObjectCollectionBase.
[Visual Basic] Imports System Imports System.Collections Imports System.Collections.Specialized Public Class MyCollection Inherits NameObjectCollectionBase Private _de As New DictionaryEntry() ' Gets a key-and-value pair (DictionaryEntry) using an index. Default Public ReadOnly Property Item(index As Integer) As DictionaryEntry Get _de.Key = Me.BaseGetKey(index) _de.Value = Me.BaseGet(index) Return _de End Get End Property ' Adds elements from an IDictionary into the new collection. Public Sub New(d As IDictionary) Dim de As DictionaryEntry For Each de In d Me.BaseAdd(CType(de.Key, [String]), de.Value) Next de End Sub 'New ' Removes an entry with the specified key from the collection. Overloads Public Sub Remove(key As [String]) Me.BaseRemove(key) End Sub 'Remove ' Removes an entry in the specified index from the collection. Overloads Public Sub Remove(index As Integer) Me.BaseRemoveAt(index) End Sub 'Remove End Class 'MyCollection Public Class SamplesNameObjectCollectionBase Public Shared Sub Main() ' Creates and initializes a new MyCollection instance. Dim d = New ListDictionary() d.Add("red", "apple") d.Add("yellow", "banana") d.Add("green", "pear") Dim myCol As New MyCollection(d) Console.WriteLine("Initial state of the collection (Count = {0}):", myCol.Count) PrintKeysAndValues(myCol) ' Removes an element at a specific index. myCol.Remove(1) Console.WriteLine("After removing the element at index 1 (Count = {0}):", myCol.Count) PrintKeysAndValues(myCol) ' Removes an element with a specific key. myCol.Remove("red") Console.WriteLine("After removing the element with the key ""red"" (Count = {0}):", myCol.Count) PrintKeysAndValues(myCol) End Sub 'Main Public Shared Sub PrintKeysAndValues(myCol As MyCollection) Dim i As Integer For i = 0 To myCol.Count - 1 Console.WriteLine("[{0}] : {1}, {2}", i, myCol(i).Key, myCol(i).Value) Next i End Sub 'PrintKeysAndValues End Class 'SamplesNameObjectCollectionBase 'This code produces the following output. ' 'Initial state of the collection (Count = 3): '[0] : red, apple '[1] : yellow, banana '[2] : green, pear 'After removing the element at index 1 (Count = 2): '[0] : red, apple '[1] : green, pear 'After removing the element with the key "red" (Count = 1): '[0] : green, pear [C#] using System; using System.Collections; using System.Collections.Specialized; public class MyCollection : NameObjectCollectionBase { private DictionaryEntry _de = new DictionaryEntry(); // Gets a key-and-value pair (DictionaryEntry) using an index. public DictionaryEntry this[ int index ] { get { _de.Key = this.BaseGetKey( index ); _de.Value = this.BaseGet( index ); return( _de ); } } // Adds elements from an IDictionary into the new collection. public MyCollection( IDictionary d ) { foreach ( DictionaryEntry de in d ) { this.BaseAdd( (String) de.Key, de.Value ); } } // Removes an entry with the specified key from the collection. public void Remove( String key ) { this.BaseRemove( key ); } // Removes an entry in the specified index from the collection. public void Remove( int index ) { this.BaseRemoveAt( index ); } } public class SamplesNameObjectCollectionBase { public static void Main() { // Creates and initializes a new MyCollection instance. IDictionary d = new ListDictionary(); d.Add( "red", "apple" ); d.Add( "yellow", "banana" ); d.Add( "green", "pear" ); MyCollection myCol = new MyCollection( d ); Console.WriteLine( "Initial state of the collection (Count = {0}):", myCol.Count ); PrintKeysAndValues( myCol ); // Removes an element at a specific index. myCol.Remove( 1 ); Console.WriteLine( "After removing the element at index 1 (Count = {0}):", myCol.Count ); PrintKeysAndValues( myCol ); // Removes an element with a specific key. myCol.Remove( "red" ); Console.WriteLine( "After removing the element with the key \"red\" (Count = {0}):", myCol.Count ); PrintKeysAndValues( myCol ); } public static void PrintKeysAndValues( MyCollection myCol ) { for ( int i = 0; i < myCol.Count; i++ ) { Console.WriteLine( "[{0}] : {1}, {2}", i, myCol[i].Key, myCol[i].Value ); } } } /* This code produces the following output. Initial state of the collection (Count = 3): [0] : red, apple [1] : yellow, banana [2] : green, pear After removing the element at index 1 (Count = 2): [0] : red, apple [1] : green, pear After removing the element with the key "red" (Count = 1): [0] : green, pear */ [C++] #using <mscorlib.dll> #using <system.dll> using namespace System; using namespace System::Collections; using namespace System::Collections::Specialized; public __gc class MyCollection : public NameObjectCollectionBase { private: DictionaryEntry _de; public: // Gets a key-and-value pair (DictionaryEntry) using an index. __property DictionaryEntry get_Item( int index ) { _de.Key = this->BaseGetKey(index); _de.Value = this->BaseGet(index); return(_de); } // Adds elements from an IDictionary* into the new collection. MyCollection(IDictionary* d) { IEnumerator* myEnum = d->GetEnumerator(); while (myEnum->MoveNext()) { DictionaryEntry* de = __try_cast<DictionaryEntry*>(myEnum->Current); this->BaseAdd(__try_cast<String*>(de->Key), de->Value); } } // Removes an entry with the specified key from the collection. void Remove(String* key) { this->BaseRemove(key); } // Removes an entry in the specified index from the collection. void Remove(int index) { this->BaseRemoveAt(index); } }; void PrintKeysAndValues(MyCollection* myCol) { for (int i = 0; i < myCol->Count; i++) { Console::WriteLine(S"[{0}] : {1}, {2}", __box(i), myCol->Item[i].Key, myCol->Item[i].Value); } }; int main() { // Creates and initializes a new MyCollection instance. IDictionary* d = new ListDictionary(); d->Add(S"red", S"apple"); d->Add(S"yellow", S"banana"); d->Add(S"green", S"pear"); MyCollection* myCol = new MyCollection(d); Console::WriteLine(S"Initial state of the collection (Count = {0}):", __box(myCol->Count)); PrintKeysAndValues(myCol); // Removes an element at a specific index. myCol->Remove(1); Console::WriteLine(S"After removing the element at index 1 (Count = {0}):", __box(myCol->Count)); PrintKeysAndValues(myCol); // Removes an element with a specific key. myCol->Remove(S"red"); Console::WriteLine(S"After removing the element with the key \"red\" (Count = {0}):", __box(myCol->Count)); PrintKeysAndValues(myCol); } /* This code produces the following output. Initial state of the collection (Count = 3): [0] : red, apple [1] : yellow, banana [2] : green, pear After removing the element at index 1 (Count = 2): [0] : red, apple [1] : green, pear After removing the element with the key "red" (Count = 1): [0] : green, pear */
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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
NameObjectCollectionBase Class | NameObjectCollectionBase Members | System.Collections.Specialized Namespace