StringDictionary.ContainsKey(String) Méthode
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Détermine si StringDictionary contient une clé spécifique.
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
- key
- String
Clé à rechercher dans StringDictionary.
true
si StringDictionary contient une entrée avec la clé spécifiée ; sinon, false
.
La clé est null
.
L’exemple de code suivant recherche un élément dans un 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".
La clé est gérée de manière non respectant la casse ; il est traduit en minuscules avant d’être utilisé.
Cette méthode est une opération O(1).
À compter de .NET Framework 2.0, cette méthode utilise les objets et CompareTo les Equals méthodes item
de la collection pour déterminer s’il item
existe. Dans les versions antérieures du .NET Framework, cette détermination a été effectuée à l’aide Equals des méthodes et CompareTo du item
paramètre sur les objets de la collection.
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