static void Main(string[] args) { Hashtable ht = new Hashtable(); ht.Add("1", "Akshay"); ht.Add("2", "Hari"); ht.Add("3", "Raghvan"); ht.Add(4, "Milind"); ht.Add('m', null); //0 ht.Add("Mahesh", null); //1 ht.Add(10, 30); //2 ht.Add(12, 30); //3 ht.Add("12", 55.43); //4 ICollection key = ht.Keys; Console.WriteLine("Retrieving all elements: "); Console.WriteLine(); foreach (var i in key) { Console.WriteLine(i + ":" + ht[i]); } Console.WriteLine(); Console.WriteLine("Retrieving all Keys: "); foreach (var i in key) { Console.WriteLine(i); } Console.WriteLine("it is read only :" + ht.IsReadOnly); Console.WriteLine("it is Synchronized :" + ht.IsSynchronized); ht.Clear(); Console.WriteLine("Capacity of Array " + ht.AsParallel()); Console.WriteLine(); }