.NET Framework Class Library
NameObjectCollectionBase.BaseClear Method
Removes all entries from the NameObjectCollectionBase instance.
Assembly: System (in System.dll)
Syntax
Visual Basic
Protected Sub BaseClear
C#
protected void BaseClear()
Visual C++
protected: void BaseClear()
F#
member BaseClear : unit -> unit
Exceptions
| Exception | Condition |
|---|---|
| NotSupportedException |
The collection is read-only. |
Remarks
Count is set to zero, and references to other objects from elements of the collection are also released.
This method is an O(1) operation.
Examples
The following code example uses BaseClear to remove all 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 ' Clears all the elements in the collection. Public Sub Clear() Me.BaseClear() End Sub 'Clear 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 all elements from the collection. myCol.Clear() Console.WriteLine("After clearing the collection (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 clearing the collection (Count = 0):
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 ); } } // Clears all the elements in the collection. public void Clear() { this.BaseClear(); } } 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 all elements from the collection. myCol.Clear(); Console.WriteLine( "After clearing the collection (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 clearing the collection (Count = 0): */
Visual C++
#using <system.dll> using namespace System; using namespace System::Collections; using namespace System::Collections::Specialized; public ref class MyCollection: public NameObjectCollectionBase { private: DictionaryEntry _de; public: property DictionaryEntry Item [ int ] { // Gets a key-and-value pair (DictionaryEntry) using an index. DictionaryEntry get( 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 = safe_cast<DictionaryEntry^>(myEnum->Current); this->BaseAdd( safe_cast<String^>(de->Key), de->Value ); } } // Clears all the elements in the collection. void Clear() { this->BaseClear(); } }; static void PrintKeysAndValues( MyCollection^ myCol ) { for ( int i = 0; i < myCol->Count; i++ ) { Console::WriteLine( "[{0}] : {1}, {2}", i, myCol->Item[ i ].Key, myCol->Item[ i ].Value ); } } int main() { // Creates and initializes a new MyCollection instance. IDictionary^ d = gcnew ListDictionary; d->Add( "red", "apple" ); d->Add( "yellow", "banana" ); d->Add( "green", "pear" ); MyCollection^ myCol = gcnew MyCollection( d ); Console::WriteLine( "Initial state of the collection (Count = {0}):", myCol->Count ); PrintKeysAndValues( myCol ); // Removes all elements from the collection. myCol->Clear(); Console::WriteLine( "After clearing the collection (Count = {0}):", 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 clearing the collection (Count = 0): */
Version Information
.NET Framework
Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0.NET Framework Client Profile
Supported in: 4, 3.5 SP1Platforms
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
See Also