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StringDictionary.Item Property

Gets or sets the value associated with the specified key.

[C#] In C#, this property is the indexer for the StringDictionary class.

[Visual Basic]
Public Overridable Default Property Item( _
   ByVal key As String _
) As String
[C#]
public virtual string this[
 string key
] {get; set;}
[C++]
public: __property virtual String* get_Item(
 String* key
);
public: __property virtual void set_Item(
 String* key,
   String*
);
[JScript]
returnValue = StringDictionaryObject.Item(key);
StringDictionaryObject.Item(key) = returnValue;
-or-
returnValue = StringDictionaryObject(key);
StringDictionaryObject(key) = returnValue;

[JScript] In JScript, you can use the default indexed properties defined by a type, but you cannot explicitly define your own. However, specifying the expando attribute on a class automatically provides a default indexed property whose type is Object and whose index type is String.

Arguments [JScript]

key
The key whose value to get or set.

Parameters [Visual Basic, C#, C++]

key
The key whose value to get or set.

Property Value

The value associated with the specified key. If the specified key is not found, Get returns a null reference (Nothing in Visual Basic), and Set creates a new entry with the specified key.

Exceptions

Exception Type Condition
NullReferenceException key is a null reference (Nothing in Visual Basic).

Remarks

The key is handled in a case-insensitive manner; it is translated to lower case before it is used.

A key cannot be a null reference (Nothing in Visual Basic), but a value can. To distinguish between a null reference (Nothing) that is returned because the specified key is not found and a null reference (Nothing) that is returned because the value of the specified key is a null reference (Nothing), use the ContainsKey method to determine if the key exists in the list.

Example

[Visual Basic, C#, C++] The following code example enumerates the elements of a StringDictionary.

[Visual Basic] 
Imports System
Imports System.Collections
Imports System.Collections.Specialized

Public Class SamplesStringDictionary   

   Public Shared Sub Main()

      ' Creates and initializes a new StringDictionary.
      Dim myCol As New StringDictionary()
      myCol.Add("red", "rojo")
      myCol.Add("green", "verde")
      myCol.Add("blue", "azul")

      ' Displays the values in the StringDictionary in two different ways.
      Console.WriteLine("Displays the elements using for each:")
      PrintKeysAndValues(myCol)
      Console.WriteLine("Displays the elements using the Keys, Values, Count, and indexer properties:")
      PrintKeysAndValues2(myCol)

   End Sub 'Main

   Public Shared Sub PrintKeysAndValues(myCol As StringDictionary)
      Dim de As DictionaryEntry

      Console.WriteLine("   KEY        VALUE")
      For Each de In  myCol
         Console.WriteLine("   {0,-10} {1}", de.Key, de.Value)
      Next de
      Console.WriteLine()

   End Sub 'PrintKeysAndValues

   Public Shared Sub PrintKeysAndValues2(myCol As StringDictionary)
      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}]     {1,-10} {2}", i, myKeys(i), myCol(myKeys(i)))
      Next i
      Console.WriteLine()

   End Sub 'PrintKeysAndValues2

End Class 'SamplesStringDictionary 


'This code produces the following output.
'
'Displays the elements using for each:
'   KEY        VALUE
'   green      verde
'   red        rojo
'   blue       azul
'
'Displays the elements using the Keys, Values, Count, and indexer properties:
'   [INDEX] KEY        VALUE
'   [0]     green      verde
'   [1]     red        rojo
'   [2]     blue       azul
'


[C#] 
using System;
using System.Collections;
using System.Collections.Specialized;

public class SamplesStringDictionary  {

   public static void Main()  {

      // Creates and initializes a new StringDictionary.
      StringDictionary myCol = new StringDictionary();
      myCol.Add( "red", "rojo" );
      myCol.Add( "green", "verde" );
      myCol.Add( "blue", "azul" );

      // Displays the values in the StringDictionary in two different ways.
      Console.WriteLine( "Displays the elements using foreach:" );
      PrintKeysAndValues( myCol );
      Console.WriteLine( "Displays the elements using the Keys, Values, Count, and indexer properties:" );
      PrintKeysAndValues2( myCol );

   }

   public static void PrintKeysAndValues( StringDictionary myCol )  {
      Console.WriteLine( "   KEY        VALUE" );
      foreach ( DictionaryEntry de in myCol )
         Console.WriteLine( "   {0,-10} {1}", de.Key, de.Value );
      Console.WriteLine();
   }

   public static void PrintKeysAndValues2( StringDictionary 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}]     {1,-10} {2}", i, myKeys[i], myCol[myKeys[i]] );
      Console.WriteLine();
   }


}

/*
This code produces the following output.

Displays the elements using foreach:
   KEY        VALUE
   green      verde
   red        rojo
   blue       azul

Displays the elements using the Keys, Values, Count, and indexer properties:
   [INDEX] KEY        VALUE
   [0]     green      verde
   [1]     red        rojo
   [2]     blue       azul

*/

[C++] 
#using <mscorlib.dll>
#using <System.dll>
using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;

void PrintKeysAndValues( StringDictionary* myCol )  {
   Console::WriteLine( S"   KEY        VALUE" );
   IEnumerator* enum0 = myCol->GetEnumerator();
   while (enum0->MoveNext())
   {
      DictionaryEntry* de = __try_cast<DictionaryEntry*>(enum0->Current);
      Console::WriteLine( S"   {0,-10} {1}", de->Key, de->Value );
   }
   Console::WriteLine();
}

void PrintKeysAndValues2( StringDictionary* myCol )  {
   String* myKeys[] = static_cast<String*[]>( Array::CreateInstance( __typeof(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}]     {1,-10} {2}", __box(i), myKeys[i], myCol->Item[myKeys[i]] );
   Console::WriteLine();
}

int main()  {

   // Creates and initializes a new StringDictionary.
   StringDictionary* myCol = new StringDictionary();
   myCol->Add( S"red", S"rojo" );
   myCol->Add( S"green", S"verde" );
   myCol->Add( S"blue", S"azul" );

   // Displays the values in the StringDictionary in two different ways.
   Console::WriteLine( S"Displays the elements using foreach:" );
   PrintKeysAndValues( myCol );
   Console::WriteLine( S"Displays the elements using the Keys, Values, Count, and indexer properties:" );
   PrintKeysAndValues2( myCol );

}

/*
This code produces the following output.

Displays the elements using foreach:
   KEY        VALUE
   green      verde
   red        rojo
   blue       azul

Displays the elements using the Keys, Values, Count, and indexer properties:
   [INDEX] KEY        VALUE
   [0]     green      verde
   [1]     red        rojo
   [2]     blue       azul

*/

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

StringDictionary Class | StringDictionary Members | System.Collections.Specialized Namespace | Performing Culture-Insensitive String Operations

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