How to Create a Dictionary of Dictionaries in C#

We can create a dictionary of dictionaries in C# by declaring a dictionary where the value type is another dictionary. This example demonstrates how to declare and initialize a dictionary of dictionaries, add key-value pairs to the inner dictionaries, and print the resulting nested dictionary.

For example,

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Declare and initialize a dictionary of dictionaries
        Dictionary<string, Dictionary<string, int>> outerDict = new Dictionary<string, Dictionary<string, int>>
        {
            { "A", new Dictionary<string, int> { { "X", 1 }, { "Y", 2 } } },
            { "B", new Dictionary<string, int> { { "Z", 3 } } }
        };

        // Print the resulting nested dictionary
        Console.WriteLine("Dictionary of dictionaries:");
        foreach (var outerKvp in outerDict)
        {
            Console.WriteLine("Key: {0}", outerKvp.Key);
            foreach (var innerKvp in outerKvp.Value)
            {
                Console.WriteLine("  Inner Key: {0}, Value: {1}", innerKvp.Key, innerKvp.Value);
            }
        }
    }
}

Dictionary of dictionaries:
Key: A
  Inner Key: X, Value: 1
  Inner Key: Y, Value: 2
Key: B
  Inner Key: Z, Value: 3

We can create and add to a dictionary of dictionaries dynamically in C# by declaring a dictionary where the value type is another dictionary. This example demonstrates how to declare the outer dictionary, add inner dictionaries dynamically, add key-value pairs to the inner dictionaries, and print the resulting nested dictionary.

For example,

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Declare the outer dictionary
        Dictionary<string, Dictionary<string, int>> outerDict = new Dictionary<string, Dictionary<string, int>>();

        // Add inner dictionaries dynamically
        outerDict["A"] = new Dictionary<string, int>();
        outerDict["B"] = new Dictionary<string, int>();

        // Add key-value pairs to the inner dictionaries
        outerDict["A"]["X"] = 1;
        outerDict["A"]["Y"] = 2;
        outerDict["B"]["Z"] = 3;

        // Print the resulting nested dictionary
        Console.WriteLine("Dictionary of dictionaries:");
        foreach (var outerKvp in outerDict)
        {
            Console.WriteLine("Key: {0}", outerKvp.Key);
            foreach (var innerKvp in outerKvp.Value)
            {
                Console.WriteLine("  Inner Key: {0}, Value: {1}", innerKvp.Key, innerKvp.Value);
            }
        }
    }
}

Dictionary of dictionaries:
Key: A
  Inner Key: X, Value: 1
  Inner Key: Y, Value: 2
Key: B
  Inner Key: Z, Value: 3