How to Clear all Key-Value Pairs from a Dictionary in C#

How to Clear all Key-Value Pairs from a Dictionary in C# ?

Answer

To clear all key-value pairs from a dictionary in C#, you can use the `Clear` method of the `Dictionary` class from the `System.Collections.Generic` namespace. This method removes all elements from the dictionary, making it empty.

✐ Examples

1 Clearing All Key-Value Pairs Using the `Clear` Method

We can clear all key-value pairs from a dictionary in C# using the `Clear` method. This example demonstrates how to remove all elements from the dictionary and print the dictionary contents before and after the clearing operation.

For example,

We start by including the necessary namespace: using System.Collections.Generic;.
We declare and initialize a dictionary named myDictionary with integer keys and string values.
We print the dictionary contents before clearing.
We use the `Clear` method to remove all key-value pairs from the dictionary.
We print the dictionary contents after clearing to confirm that it is empty.

C# Program

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Declare and initialize a dictionary
        Dictionary<int, string> myDictionary = new Dictionary<int, string>
        {
            {1, "One"},
            {2, "Two"},
            {3, "Three"}
        };

        // Print the dictionary contents before clearing
        Console.WriteLine("Dictionary contents before clearing:");
        foreach (KeyValuePair<int, string> kvp in myDictionary)
        {
            Console.WriteLine("Key: {0}, Value: {1}", kvp.Key, kvp.Value);
        }

        // Clear all key-value pairs from the dictionary
        myDictionary.Clear();

        // Print the dictionary contents after clearing
        Console.WriteLine("Dictionary contents after clearing:");
        foreach (KeyValuePair<int, string> kvp in myDictionary)
        {
            Console.WriteLine("Key: {0}, Value: {1}", kvp.Key, kvp.Value);
        }
    }
}

Output

Dictionary contents before clearing:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Dictionary contents after clearing:

2 Confirming the Dictionary is Empty After Clearing

We can clear all key-value pairs from a dictionary in C# and confirm that it is empty by checking the `Count` property. This example demonstrates how to clear the dictionary and verify that it is empty.

For example,

We start by including the necessary namespace: using System.Collections.Generic;.
We declare and initialize a dictionary named myDictionary with integer keys and string values.
We print the dictionary contents before clearing.
We use the `Clear` method to remove all key-value pairs from the dictionary.
We check the `Count` property to confirm that the dictionary is empty.

C# Program

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Declare and initialize a dictionary
        Dictionary<int, string> myDictionary = new Dictionary<int, string>
        {
            {1, "One"},
            {2, "Two"},
            {3, "Three"}
        };

        // Print the dictionary contents before clearing
        Console.WriteLine("Dictionary contents before clearing:");
        foreach (KeyValuePair<int, string> kvp in myDictionary)
        {
            Console.WriteLine("Key: {0}, Value: {1}", kvp.Key, kvp.Value);
        }

        // Clear all key-value pairs from the dictionary
        myDictionary.Clear();

        // Confirm the dictionary is empty
        if (myDictionary.Count == 0)
        {
            Console.WriteLine("The dictionary is now empty.");
        }
        else
        {
            Console.WriteLine("The dictionary is not empty.");
        }
    }
}

Output

Dictionary contents before clearing:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
The dictionary is now empty.

Summary

In this tutorial, we learned How to Clear all Key-Value Pairs from a Dictionary in C# language with well detailed examples.

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