using System;

using System.Collections.Generic;

using System.Linq;

​

public class Person

{

    public string ID { get; set; }

    public string Name { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        // Create a list of persons

        List<Person> persons = new List<Person>

        {

            new Person { ID = "ABC123", Name = "John" },

            new Person { ID = "DEF456", Name = "Alice" },

            new Person { ID = "GHI789", Name = "Bob" }

        };

​

        // Convert the list to a case-insensitive dictionary

        Dictionary<string, Person> dictionary = persons.ToDictionary(person => person.ID, StringComparer.OrdinalIgnoreCase);

​

        // Check if the dictionary contains a specific ID

        string idToCheck = "abc123";

        bool containsID = dictionary.ContainsKey(idToCheck);

​

        Console.WriteLine("Dictionary contains ID '{0}': {1}", idToCheck, containsID);

    }

}