SortedList<TKey,TValue>.ContainsKey(TKey) Metoda

Definicja

Określa, czy SortedList<TKey,TValue> zawiera określony klucz.Determines whether the SortedList<TKey,TValue> contains a specific key.

public:
 virtual bool ContainsKey(TKey key);
public bool ContainsKey (TKey key);
abstract member ContainsKey : 'Key -> bool
override this.ContainsKey : 'Key -> bool
Public Function ContainsKey (key As TKey) As Boolean

Parametry

key
TKey

Klucz, który ma zostać zlokalizowany w SortedList<TKey,TValue> .The key to locate in the SortedList<TKey,TValue>.

Zwraca

Boolean

true Jeśli SortedList<TKey,TValue> zawiera element z określonym kluczem; w przeciwnym razie, false .true if the SortedList<TKey,TValue> contains an element with the specified key; otherwise, false.

Implementuje

Wyjątki

key to null.key is null.

Przykłady

Poniższy przykład kodu pokazuje, jak używać ContainsKey metody do testowania, czy klucz istnieje przed wywołaniem Add metody.The following code example shows how to use the ContainsKey method to test whether a key exists prior to calling the Add method. Pokazano również, jak używać TryGetValue metody do pobierania wartości, co jest wydajnym sposobem pobierania wartości, gdy program często próbuje klucze, które nie znajdują się na sortowanej liście.It also shows how to use the TryGetValue method to retrieve values, which is an efficient way to retrieve values when a program frequently tries keys that are not in the sorted list. Na koniec pokazuje najmniej wydajny sposób, aby sprawdzić, czy klucze istnieją, przy użyciu Item[] właściwości (indeksator w języku C#).Finally, it shows the least efficient way to test whether keys exist, by using the Item[] property (the indexer in C#).

Ten przykład kodu jest częścią większego przykładu dostarczonego dla SortedList<TKey,TValue> klasy.This code example is part of a larger example provided for the SortedList<TKey,TValue> class.

// ContainsKey can be used to test keys before inserting
// them.
if (!openWith->ContainsKey("ht"))
{
    openWith->Add("ht", "hypertrm.exe");
    Console::WriteLine("Value added for key = \"ht\": {0}",
        openWith["ht"]);
}
// ContainsKey can be used to test keys before inserting
// them.
if (!openWith.ContainsKey("ht"))
{
    openWith.Add("ht", "hypertrm.exe");
    Console.WriteLine("Value added for key = \"ht\": {0}",
        openWith["ht"]);
}
' ContainsKey can be used to test keys before inserting 
' them.
If Not openWith.ContainsKey("ht") Then
    openWith.Add("ht", "hypertrm.exe")
    Console.WriteLine("Value added for key = ""ht"": {0}", _
        openWith("ht"))
End If
// When a program often has to try keys that turn out not to
// be in the list, TryGetValue can be a more efficient
// way to retrieve values.
String^ value = "";
if (openWith->TryGetValue("tif", value))
{
    Console::WriteLine("For key = \"tif\", value = {0}.", value);
}
else
{
    Console::WriteLine("Key = \"tif\" is not found.");
}
// When a program often has to try keys that turn out not to
// be in the list, TryGetValue can be a more efficient
// way to retrieve values.
string value = "";
if (openWith.TryGetValue("tif", out value))
{
    Console.WriteLine("For key = \"tif\", value = {0}.", value);
}
else
{
    Console.WriteLine("Key = \"tif\" is not found.");
}
' When a program often has to try keys that turn out not to
' be in the list, TryGetValue can be a more efficient 
' way to retrieve values.
Dim value As String = ""
If openWith.TryGetValue("tif", value) Then
    Console.WriteLine("For key = ""tif"", value = {0}.", value)
Else
    Console.WriteLine("Key = ""tif"" is not found.")
End If
// The indexer throws an exception if the requested key is
// not in the list.
try
{
    Console::WriteLine("For key = \"tif\", value = {0}.",
        openWith["tif"]);
}
catch (KeyNotFoundException^)
{
    Console::WriteLine("Key = \"tif\" is not found.");
}
// The indexer throws an exception if the requested key is
// not in the list.
try
{
    Console.WriteLine("For key = \"tif\", value = {0}.",
        openWith["tif"]);
}
catch (KeyNotFoundException)
{
    Console.WriteLine("Key = \"tif\" is not found.");
}
' The default Item property throws an exception if the requested
' key is not in the list.
Try
    Console.WriteLine("For key = ""tif"", value = {0}.", _
        openWith("tif"))
Catch 
    Console.WriteLine("Key = ""tif"" is not found.")
End Try

Uwagi

Ta metoda jest operacją O (log n ), gdzie n is Count .This method is an O(log n) operation, where n is Count.

Dotyczy

Zobacz też