/*

A SortedSet<T> object maintains a sorted order without affecting performance as elements are inserted and deleted.

Duplicate elements are not allowed.

*/

using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        // choose the string comparer you want and uncomment that one

            //var bigCities = new SortedSet<string>() { "New York", "Manchester", "Sheffield", "Paris" };

            var bigCities = new SortedSet<string>(StringComparer.InvariantCultureIgnoreCase) { "New York", "Manchester", "Sheffield", "Paris" };

            //var bigCities = new SortedSet<string>(new UncasedStringComparer()) { "New York", "Manchester", "Sheffield", "Paris" };

​

            bigCities.Add("SHEFFIELD");

            bigCities.Add("BEIJING");

​

            foreach (string city in bigCities)

                Console.WriteLine(city);

        }

​

​

    }

​

    class UncasedStringComparer : IComparer<string>

    {

​

        public int Compare(string x, string y)

        {

            return string.Compare(x, y, StringComparison.InvariantCultureIgnoreCase);

        }

    }

​