StringDictionary.ContainsKey(String) Metoda

Definicja

Przestrzeń nazw:

System.Collections.Specialized

Zestaw:

System.Collections.Specialized.dll

Źródło:

StringDictionary.cs

Określa, czy element StringDictionary zawiera określony klucz.

public:
 virtual bool ContainsKey(System::String ^ key);

public virtual bool ContainsKey (string key);

abstract member ContainsKey : string -> bool
override this.ContainsKey : string -> bool

Public Overridable Function ContainsKey (key As String) As Boolean

Parametry

key

String

Klucz do zlokalizowania w pliku StringDictionary.

Zwraca

Boolean

true jeśli element StringDictionary zawiera wpis z określonym kluczem; w przeciwnym razie falsewartość .

Wyjątki

ArgumentNullException

Klucz to null.

Przykłady

Poniższy przykład kodu wyszukuje element w elemecie StringDictionary.

#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;
void PrintKeysAndValues( StringDictionary^ myCol )
{
   Console::WriteLine( "   KEY        VALUE" );
   IEnumerator^ enum0 = myCol->GetEnumerator();
   while ( enum0->MoveNext() )
   {
      DictionaryEntry^ de = safe_cast<DictionaryEntry^>(enum0->Current);
      Console::WriteLine( "   {0,-10} {1}", de->Key, de->Value );
   }

   Console::WriteLine();
}

int main()
{
   
   // Creates and initializes a new StringDictionary.
   StringDictionary^ myCol = gcnew StringDictionary;
   myCol->Add( "red", "rojo" );
   myCol->Add( "green", "verde" );
   myCol->Add( "blue", "azul" );
   
   // Displays the values in the StringDictionary.
   Console::WriteLine( "Initial contents of the StringDictionary:" );
   PrintKeysAndValues( myCol );
   
   // Searches for a key.
   if ( myCol->ContainsKey( "red" ) )
      Console::WriteLine( "The collection contains the key \"red\"." );
   else
      Console::WriteLine( "The collection does not contain the key \"red\"." );

   Console::WriteLine();
   
   // Searches for a value.
   if ( myCol->ContainsValue( "amarillo" ) )
      Console::WriteLine( "The collection contains the value \"amarillo\"." );
   else
      Console::WriteLine( "The collection does not contain the value \"amarillo\"." );

   Console::WriteLine();
}

/*
This code produces the following output.

Initial contents of the StringDictionary:
   KEY        VALUE
   green      verde
   red        rojo
   blue       azul

The collection contains the key "red".

The collection does not contain the value "amarillo".

*/

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.
      Console.WriteLine( "Initial contents of the StringDictionary:" );
      PrintKeysAndValues( myCol );

      // Searches for a key.
      if ( myCol.ContainsKey( "red" ) )
         Console.WriteLine( "The collection contains the key \"red\"." );
      else
         Console.WriteLine( "The collection does not contain the key \"red\"." );
      Console.WriteLine();

      // Searches for a value.
      if ( myCol.ContainsValue( "amarillo" ) )
         Console.WriteLine( "The collection contains the value \"amarillo\"." );
      else
         Console.WriteLine( "The collection does not contain the value \"amarillo\"." );
      Console.WriteLine();
   }

   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();
   }
}

/*
This code produces the following output.

Initial contents of the StringDictionary:
   KEY        VALUE
   green      verde
   red        rojo
   blue       azul

The collection contains the key "red".

The collection does not contain the value "amarillo".

*/

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.
      Console.WriteLine("Initial contents of the StringDictionary:")
      PrintKeysAndValues(myCol)

      ' Searches for a key.
      If myCol.ContainsKey("red") Then
         Console.WriteLine("The collection contains the key ""red"".")
      Else
         Console.WriteLine("The collection does not contain the key ""red"".")
      End If
      Console.WriteLine()

      ' Searches for a value.
      If myCol.ContainsValue("amarillo") Then
         Console.WriteLine("The collection contains the value ""amarillo"".")
      Else
         Console.WriteLine("The collection does not contain the value ""amarillo"".")
      End If
      Console.WriteLine()

   End Sub

   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

End Class


'This code produces the following output.
'
'Initial contents of the StringDictionary:
'   KEY        VALUE
'   green      verde
'   red        rojo
'   blue       azul
'
'The collection contains the key "red".
'
'The collection does not contain the value "amarillo".

Uwagi

Klucz jest obsługiwany w sposób niewrażliwy na wielkość liter; jest tłumaczona na małe litery, zanim zostanie użyta.

Ta metoda jest operacją O(1).

Począwszy od .NET Framework 2.0, ta metoda używa metod item i CompareTo obiektów Equals kolekcji do określenia, czy item istnieje. We wcześniejszych wersjach .NET Framework ta determinacja została wykonana przy użyciu Equals metod item i CompareTo parametru w obiektach w kolekcji.

Zobacz też

• Wykonywanie niezależnych od kultury operacji na ciągach