IDictionary.Contains(Object) 方法

定義

判斷 IDictionary 物件是否包含具有指定索引鍵的項目。Determines whether the IDictionary object contains an element with the specified key.

public:
 bool Contains(System::Object ^ key);
public bool Contains (object key);
abstract member Contains : obj -> bool
Public Function Contains (key As Object) As Boolean

參數

key
Object

要在 IDictionary 物件中尋找的索引鍵。The key to locate in the IDictionary object.

傳回

如果 true 包含具有該索引鍵的項目,則為 IDictionary,否則為 falsetrue if the IDictionary contains an element with the key; otherwise, false.

例外狀況

keynullkey is null.

範例

下列程式碼範例示範如何執行Contains方法。The following code example demonstrates how to implement the Contains method. 這個程式碼範例是針對IDictionary類別提供之較大範例的一部分。This code example is part of a larger example provided for the IDictionary class.

public:
    virtual bool Contains(Object^ key)
    {
        int index;
        return TryGetIndexOfKey(key, &index);
    }
public bool Contains(object key)
{
   Int32 index;
   return TryGetIndexOfKey(key, out index);
}
Public Function Contains(ByVal key As Object) As Boolean Implements IDictionary.Contains
    Dim index As Integer
    Return TryGetIndexOfKey(key, index)
End Function

備註

不論是否允許索引鍵, 都可能會有null不同的執行方式。Implementations can vary in whether they allow the key to be null.

從 .NET Framework 2.0 開始, 這個方法會Equals在上item使用集合的物件和CompareTo方法, 以判斷是否item存在。Starting with the .NET Framework 2.0, this method uses the collection's objects' Equals and CompareTo methods on item to determine whether item exists. 在舊版的 .NET Framework 中, 會在集合中的物件上使用Equals item參數的CompareTo和方法來進行這項判斷。In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the item parameter on the objects in the collection.

適用於