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📜  C#|检查OrderedDictionary集合是否包含特定键

📅  最后修改于: 2021-05-29 22:06:14             🧑  作者: Mango

OrderedDictionary.Contains(Object)方法用于检查OrderedDictionary集合是否包含特定键。

句法:

public bool Contains (object key);

在这里, key是要在OrderedDictionary集合中找到的键。

返回值:如果OrderedDictionary集合包含具有指定键的元素,则此方法返回True ,否则返回False

下面给出了一些示例,以更好地理解实现:

范例1:

// C# code to check if OrderedDictionary
// collection contains a specific key
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver method
    public static void Main()
    {
  
        // Creating a orderedDictionary named myDict
        OrderedDictionary myDict = new OrderedDictionary();
  
        // Adding key and value in myDict
        myDict.Add("key1", "value1");
        myDict.Add("key2", "value2");
        myDict.Add("key3", "value3");
        myDict.Add("key4", "value4");
        myDict.Add("key5", "value5");
  
        // Checking if OrderedDictionary
        // collection contains a specific key
        Console.WriteLine(myDict.Contains("Key6"));
    }
}

输出:

False

范例2:

// C# code to check if OrderedDictionary
// collection contains a specific key
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver method
    public static void Main()
    {
  
        // Creating a orderedDictionary named myDict
        OrderedDictionary myDict = new OrderedDictionary();
  
        // Adding key and value in myDict
        myDict.Add("key1", "value1");
        myDict.Add("key2", "value2");
        myDict.Add("key3", "value3");
        myDict.Add("key4", "value4");
        myDict.Add("key5", "value5");
  
        // Displaying the key/value pairs in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " --> " + de.Value);
  
        // Checking if OrderedDictionary collection
        // contains a specific key
        if (myDict.Contains("key4"))
            myDict.Remove("key4");
  
        // Displaying the key/value pairs in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " --> " + de.Value);
    }
}

输出:

key1 --> value1
key2 --> value2
key3 --> value3
key4 --> value4
key5 --> value5
key1 --> value1
key2 --> value2
key3 --> value3
key5 --> value5

注意:如果键不存在或键为空,则使用Item [Object]属性可以返回空值。使用Contains方法确定OrderedDictionary集合中是否存在特定的键。

参考:
https://docs.microsoft.com/zh-cn/dotnet/api/system.collections.specialized.ordereddictionary.contains?view=netframework-4.7.2