C# | Removing the specified key entry from HybridDictionary

HybridDictionary.Remove(Object) method is used to remove the entry with the specified key from the HybridDictionary.

Syntax:

public void Remove (object key);

Here, key is the key of the entry to remove.

Exception: This method throws ArgumentNullException if the key is null.

Below given are some examples to understand the implementation in a better way :

Example 1:

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// C# code to remove the entry
// with the specified key from
// the HybridDictionary.
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a HybridDictionary named myDict
        HybridDictionary myDict = new HybridDictionary();
  
        // Adding key/value pairs in myDict
        myDict.Add("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");
        myDict.Add("E", "Elephant");
        myDict.Add("F", "Fish");
  
        // Displaying the number of key/value
        // pairs in HybridDictionary myDict
        Console.WriteLine("Number of key/value pairs in myDict are : " 
                                                      + myDict.Count);
  
        // Displaying the key/value pairs in myDict
        Console.WriteLine("The key/value pairs in myDict are : ");
  
        foreach(DictionaryEntry de in myDict)
        {
            Console.WriteLine(de.Key + " --> " + de.Value);
        }
  
        // Removing the entry with the
        // specified key from the HybridDictionary.
        myDict.Remove("C");
  
        // Displaying the number of key/value
        // pairs in HybridDictionary myDict
        Console.WriteLine("Number of key/value pairs in myDict are : " 
                                                      + myDict.Count);
  
        // Displaying the key/value pairs in myDict
        Console.WriteLine("The key/value pairs in myDict are : ");
  
        foreach(DictionaryEntry de in myDict)
        {
            Console.WriteLine(de.Key + " --> " + de.Value);
        }
    }
}

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Output:


Number of key/value pairs in myDict are : 6
The key/value pairs in myDict are : 
A --> Apple
B --> Banana
C --> Cat
D --> Dog
E --> Elephant
F --> Fish
Number of key/value pairs in myDict are : 5
The key/value pairs in myDict are : 
A --> Apple
B --> Banana
D --> Dog
E --> Elephant
F --> Fish



Example 2:











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// C# code to remove the entry 


// with the specified key from 


// the HybridDictionary. 


using System; 


using System.Collections; 


using System.Collections.Specialized; 


  


class GFG { 


  


    // Driver code 


    public static void Main() 


    { 


  


        // Creating a HybridDictionary named myDict 


        HybridDictionary myDict = new HybridDictionary(); 


  


        // Adding key/value pairs in myDict 


        myDict.Add("I", "first"); 


        myDict.Add("II", "second"); 


        myDict.Add("III", "third"); 


        myDict.Add("IV", "fourth"); 


        myDict.Add("V", "fifth"); 


  


        // Displaying the number of key/value 


        // pairs in HybridDictionary myDict 


        Console.WriteLine("Number of key/value pairs in myDict are : "


                                                      + myDict.Count); 


  


        // Displaying the key/value pairs in myDict 


        Console.WriteLine("The key/value pairs in myDict are : "); 


  


        foreach(DictionaryEntry de in myDict) 


        { 


            Console.WriteLine(de.Key + " --> " + de.Value); 


        } 


  


        // Removing the entry with the 


        // specified key from the HybridDictionary. 


        // This should raise "ArgumentNullException" 


        // as the key is "null" 


        myDict.Remove(null); 


  


        // Displaying the number of key/value 


        // pairs in HybridDictionary myDict 


        Console.WriteLine("Number of key/value pairs in myDict are : " 


                                                      + myDict.Count); 


  


        // Displaying the key/value pairs in myDict 


        Console.WriteLine("The key/value pairs in myDict are : "); 


  


        foreach(DictionaryEntry de in myDict) 


        { 


            Console.WriteLine(de.Key + " --> " + de.Value); 


        } 


    } 


} 



















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Runtime Error:



Unhandled Exception:

System.ArgumentNullException: Key cannot be null.

Parameter name: key



Note: 


    

  • If the HybridDictionary does not contain an element with the specified key, the HybridDictionary remains unchanged. No exception is thrown. 
    • 

  • If the collection is already stored in a Hashtable and the number of elements falls below the optimal size for a ListDictionary, the collection remains in the Hashtable to avoid the overhead of copying elements from the Hashtable back to a ListDictionary. 
    • 

  • This method is an O(1) operation.
    • 



Reference:




          
          
          
          

            

    

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