How to Add a Key-Value Pair to a Dictionary in C#

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

Answer

To add a key-value pair to a dictionary in C#, you can use the `Add` method of the `Dictionary` class from the `System.Collections.Generic` namespace. You can also use the indexer to add or update key-value pairs.

✐ Examples

1 Adding a Key-Value Pair Using the `Add` Method

We can add a key-value pair to a dictionary in C# using the `Add` method. This example demonstrates how to add key-value pairs to a dictionary and print its contents.

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 add key-value pairs to the dictionary using the `Add` method.
We print the dictionary contents to verify the key-value pairs.

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>();

        // Add key-value pairs to the dictionary
        myDictionary.Add(1, "One");
        myDictionary.Add(2, "Two");
        myDictionary.Add(3, "Three");

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

Output

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

2 Adding or Updating a Key-Value Pair Using the Indexer

We can add or update a key-value pair in a dictionary in C# using the indexer. This example demonstrates how to add or update key-value pairs in a dictionary and print its contents.

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 add or update key-value pairs in the dictionary using the indexer.
We print the dictionary contents to verify the key-value pairs.

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>();

        // Add or update key-value pairs in the dictionary using the indexer
        myDictionary[1] = "One";
        myDictionary[2] = "Two";
        myDictionary[3] = "Three";

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

Output

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

Summary

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

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How to Add a Key-Value Pair to a Dictionary in C#