Dictionary<TKey,TValue>.IDictionary.Contains(Object) Dictionary<TKey,TValue>.IDictionary.Contains(Object) Dictionary<TKey,TValue>.IDictionary.Contains(Object) Method

定義

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

 virtual bool System.Collections.IDictionary.Contains(System::Object ^ key) = System::Collections::IDictionary::Contains;
bool IDictionary.Contains (object key);
Function Contains (key As Object) As Boolean Implements IDictionary.Contains

參數

key
Object Object Object

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

傳回

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

實作

例外狀況

範例

下列程式碼範例顯示如何搭配使用IDictionary.Contains System.Collections.IDictionary介面Dictionary<TKey,TValue>的方法。The following code example shows how to use the IDictionary.Contains method of the System.Collections.IDictionary interface with a Dictionary<TKey,TValue>. 此範例示範false如果提供錯誤資料類型的索引鍵,方法會傳回。The example demonstrates that the method returns false if a key of the wrong data type is supplied.

此程式碼範例是較大範例的一部分,包括針對IDictionary.Add方法提供的輸出。The code example is part of a larger example, including output, provided for the IDictionary.Add method.

using System;
using System.Collections;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create a new dictionary of strings, with string keys,
        // and access it using the IDictionary interface.
        //
        IDictionary openWith = new Dictionary<string, string>();

        // Add some elements to the dictionary. There are no 
        // duplicate keys, but some of the values are duplicates.
        // IDictionary.Add throws an exception if incorrect types
        // are supplied for key or value.
        openWith.Add("txt", "notepad.exe");
        openWith.Add("bmp", "paint.exe");
        openWith.Add("dib", "paint.exe");
        openWith.Add("rtf", "wordpad.exe");
Imports System.Collections
Imports System.Collections.Generic

Public Class Example
    
    Public Shared Sub Main() 

        ' Create a new dictionary of strings, with string keys,
        ' and access it using the IDictionary interface.
        '
        Dim openWith As IDictionary = _
            New Dictionary(Of String, String)
        
        ' Add some elements to the dictionary. There are no 
        ' duplicate keys, but some of the values are duplicates.
        ' IDictionary.Add throws an exception if incorrect types
        ' are supplied for key or value.
        openWith.Add("txt", "notepad.exe")
        openWith.Add("bmp", "paint.exe")
        openWith.Add("dib", "paint.exe")
        openWith.Add("rtf", "wordpad.exe")
// Contains can be used to test keys before inserting 
// them.
if (!openWith.Contains("ht"))
{
    openWith.Add("ht", "hypertrm.exe");
    Console.WriteLine("Value added for key = \"ht\": {0}", 
        openWith["ht"]);
}

// IDictionary.Contains returns false if the wrong data
// type is supplied.
Console.WriteLine("openWith.Contains(29.7) returns {0}",
    openWith.Contains(29.7));
' Contains can be used to test keys before inserting 
' them.
If Not openWith.Contains("ht") Then
    openWith.Add("ht", "hypertrm.exe")
    Console.WriteLine("Value added for key = ""ht"": {0}", _
        openWith("ht"))
End If

' IDictionary.Contains returns False if the wrong data 
' type is supplied.
Console.WriteLine("openWith.Contains(29.7) returns {0}", _
    openWith.Contains(29.7))
    }
}

    End Sub

End Class

備註

false如果TKey Dictionary<TKey,TValue>的型別無法指派給的索引鍵型別,這個方法會傳回。 keyThis method returns false if key is of a type that is not assignable to the key type TKey of the Dictionary<TKey,TValue>.

這個方法會使用 O (1)運算。This method approaches an O(1) operation.

適用於