C# | Remove all elements from OrderedDictionary

OrderedDictionary.Clear method is used to remove all elements from the OrderedDictionary collection.

Syntax:

public void Clear ();

Exception: If the OrderedDictionary collection is read-only then it will throw NotSupportedException.

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

Example 1:

// C# code to remove all elements
// from OrderedDictionary
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 number of element initially
        Console.WriteLine("Number of elements are : " + myDict.Count);

        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);

        // Removing all elements from OrderedDictionary
        myDict.Clear();

        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : " + myDict.Count);

        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);
    }
}

Output:

Number of elements are : 5
key1 -- value1
key2 -- value2
key3 -- value3
key4 -- value4
key5 -- value5
Number of elements are : 0

Example 2:

// C# code to remove all elements
// from OrderedDictionary
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("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");

        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : " + myDict.Count);

        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);

        // Removing all elements from OrderedDictionary
        myDict.Clear();

        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : " + myDict.Count);

        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);
    }
}

Output:

Number of elements are : 4
A -- Apple
B -- Banana
C -- Cat
D -- Dog
Number of elements are : 0

Note:

• After calling the Clear method, the Count property is set to zero.
• References to other objects from elements of the collection are also released.
• The capacity of dictionary is not changed as a result of calling this method.

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.collections.specialized.ordereddictionary.clear?view=netframework-4.7.2