How to Remove a Key-Value Pair from a Dictionary in C# - Step by Step Examples

How to Remove a Key-Value Pair from a Dictionary in C# ?

Answer

To remove a key-value pair from a dictionary in C#, you can use the `Remove` method of the `Dictionary` class from the `System.Collections.Generic` namespace. This method removes the element with the specified key from the dictionary.

✐ Examples

1 Removing a Key-Value Pair Using the `Remove` Method

We can remove a key-value pair from a dictionary in C# using the `Remove` method. This example demonstrates how to remove a key-value pair by specifying the key and print the dictionary contents before and after the removal.

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 removing a key-value pair.
We use the `Remove` method to remove a key-value pair by specifying the key.
We print the dictionary contents after removing the key-value pair.

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

        // Key to remove
        int keyToRemove = 2;

        // Remove the key-value pair using the Remove method
        myDictionary.Remove(keyToRemove);

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

Output

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

2 Checking for Key Existence Before Removing Using `Remove` Method

We can check if a key exists before attempting to remove a key-value pair in a dictionary in C# using the `Remove` method. This example demonstrates how to check for key existence and remove the key-value pair if it exists, then print the dictionary contents before and after the removal.

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 removing a key-value pair.
We check if the key exists and use the `Remove` method to remove the key-value pair if it exists.
We print the dictionary contents after removing the key-value pair.

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

        // Key to remove
        int keyToRemove = 4;

        // Check if the key exists and remove it if it does
        if (myDictionary.ContainsKey(keyToRemove))
        {
            myDictionary.Remove(keyToRemove);
            Console.WriteLine("Key {0} was removed from the dictionary.", keyToRemove);
        }
        else
        {
            Console.WriteLine("Key {0} does not exist in the dictionary.", keyToRemove);
        }

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

Output

Dictionary contents before removal:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Key 4 does not exist in the dictionary.
Dictionary contents after removal:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three

Summary

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

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How to Remove a Key-Value Pair from a Dictionary in C# - Step by Step Examples