using System;  

 using System.Collections;  

public class Program

{

    public static void Main()

    {

        DayPlanner myDay = new DayPlanner();

        var dinner =DateTime.Parse("2006/06/26");

        var lunch =DateTime.Parse("2006/02/03");

        Console.WriteLine( $"{lunch}    {dinner}");

        myDay[lunch] = "Lunch"; 

        myDay[dinner] = "Dinner"; 

        string whatNow = myDay["2006/06/26"];

        Console.WriteLine(whatNow ?? "Nothing");

    }

}

​

 public class DayPlanner  

 {  

     // We store our indexer values in here   

     Hashtable _meetings = new Hashtable();  

​

     // First indexer  

     public string this[DateTime date] {  

         get {  

             return _meetings[date] as string;  

         }  

         set {  

             _meetings[date] = value;  

         }  

     }  

​

     // Second indexer, overloads the first  

     public string this[string datestr] {  

         get {  

             return this[DateTime.Parse(datestr)] as string;   

         }  

         set {  

             this[DateTime.Parse(datestr)] = value;  

         }  

     }  

 }