using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        // https://learn.microsoft.com/en-us/dotnet/api/system.stringcomparer.currentculture?view=net-7.0

        var dict = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase);

        dict["a"] = 1;

        dict["B"] = 2;

        dict["c"] = 3;

        dict["TEST"] = 4;

        Console.WriteLine("The dictionary<string, int> contains the following KeyValuePairs:");

        foreach (KeyValuePair<string, int> item in dict)

        {

            Console.WriteLine($"Key: {item.Key} Value: {item.Value}");

        }

        Console.WriteLine("\nBEGIN 'Dictionary<string, int>(StringComparer.OrdinalIgnoreCase)' test---\n");

        Console.WriteLine("\nCase-Insenstive results:\n-------------------------\n");

        if (dict.ContainsKey("A")) { Console.WriteLine("Dictionary contains key 'A' = true"); }

        if (dict.ContainsKey("b")) { Console.WriteLine("Dictionary contains key 'b' = true"); }

        if (dict.ContainsKey("C")) { Console.WriteLine("Dictionary contains key 'C' = true"); }

        if (dict.ContainsKey("tEst")) { Console.WriteLine("Dictionary contains key 'TEST' = true"); }

        Console.WriteLine("\nEND 'Dictionary<string, int>(StringComparer.OrdinalIgnoreCase)' test---");

    }

}