SortedDictionary<TKey,TValue>.IDictionary.Contains(Object) 方法

定义

命名空间:

System.Collections.Generic

程序集:

System.Collections.dll

Source:

SortedDictionary.cs

确定是否 IDictionary 包含带有指定键的元素。

 virtual bool System.Collections.IDictionary.Contains(System::Object ^ key) = System::Collections::IDictionary::Contains;

bool IDictionary.Contains (object key);

abstract member System.Collections.IDictionary.Contains : obj -> bool
override this.System.Collections.IDictionary.Contains : obj -> bool

Function Contains (key As Object) As Boolean Implements IDictionary.Contains

参数

key

Object

要在 IDictionary 中定位的键。

返回

Boolean

如果 true 包含具有键的元素，则为 IDictionary；否则为 false。

实现

Contains(Object)

例外

ArgumentNullException

key 为 null。

示例

下面的代码示例演示如何将 接口的 System.Collections.IDictionary 方法与 一IDictionary.Contains起使用SortedDictionary<TKey,TValue>。 该示例演示如果提供了错误数据类型的键，则方法将返回 false 。

代码示例是为 方法提供的更大示例（包括输出）的一 IDictionary.Add 部分。

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

public class Example
{
    public static void Main()
    {
        // Create a new sorted dictionary of strings, with string keys,
        // and access it using the IDictionary interface.
        //
        IDictionary openWith = new SortedDictionary<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 sorted dictionary of strings, with string keys,
        ' and access it using the IDictionary interface.
        '
        Dim openWith As IDictionary = _
            New SortedDictionary(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

注解

如果 key 的类型不可分配给 的键类型SortedDictionary<TKey,TValue>TKey，则此方法返回 false 。

此方法是 O (日志 n) 操作，其中 n 为 Count。