using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        IDictionary<int, string> numberNames = new Dictionary<int, string>();

        numberNames.Add(1,"One"); // adding key/value using Add()

        numberNames.Add(3,"Three");

        numberNames.Add(2,"Two");

        foreach(KeyValuePair<int, string> kvp in numberNames)

            Console.WriteLine("Key: {0}, Value: {1}",kvp.Key, kvp.Value);

        // creating a dictionary using collectiion-intializer syntax

        var cities = new Dictionary<string, string>(){

            {"UK","London, Manchester, Birmingham"},

            {"USA","Chicago, New York, Washington"},

            {"India","Mumbai, New Delhi, Pune"},

        };

        Console.WriteLine(cities["UK"]); // print value of UK key

        Console.WriteLine(cities["USA"]); // prints value of USA key

        //Console.WriteLine(cities["France"]);

        // use Contains.Key() to check for an unkown key

        if(cities.ContainsKey("France")){

            Console.WriteLine(cities["France"]);

        }

        //use TryGetValue() to get a value of unknown key

        string result;

        if(cities.TryGetValue("France", out result))

        {

            Console.WriteLine(result);

        }

        Console.WriteLine("---access elemts using for loop---");

        //use ElementAt() to retrieve key-value pair using index

        for (int i = 0; i < cities.Count; i++)

        {

            Console.WriteLine("Key: {0},Value: {1}",

                              cities.ElementAt(i).Key,

                              cities.ElementAt(i).Value);

        }

        foreach(var kvp in cities)

            Console.WriteLine("Key: {0}, Value: {1}", kvp.Key,kvp.Value);

    }

}