static void Main(string[] args)
{
var hashTable = new HashTable <DateTime, string>();
var date = new DateTime(1995, 7, 18);
hashTable.Add(date, "Some value");
var containsKey = hashTable.ContainsKey(date);
var grades = new HashTable <string, int>();
Console.WriteLine("Grades:" + string.Join(",", grades));
Console.WriteLine("--------------------");
grades.Add("Peter", 3);
grades.Add("Maria", 6);
grades["George"] = 5;
Console.WriteLine("Grades:" + string.Join(",", grades));
Console.WriteLine("--------------------");
grades.AddOrReplace("Peter", 33);
grades.AddOrReplace("Tanya", 4);
grades["George"] = 55;
Console.WriteLine("Grades:" + string.Join(",", grades));
Console.WriteLine("--------------------");
Console.WriteLine("Keys: " + string.Join(", ", grades.Keys));
Console.WriteLine("Values: " + string.Join(", ", grades.Values));
Console.WriteLine("Count = " + string.Join(", ", grades.Count));
Console.WriteLine("--------------------");
grades.Remove("Peter");
grades.Remove("George");
grades.Remove("George");
Console.WriteLine("Grades:" + string.Join(",", grades));
Console.WriteLine("--------------------");
Console.WriteLine("ContainsKey[\"Tanya\"] = " + grades.ContainsKey("Tanya"));
Console.WriteLine("ContainsKey[\"George\"] = " + grades.ContainsKey("George"));
Console.WriteLine("Grades[\"Tanya\"] = " + grades["Tanya"]);
Console.WriteLine("--------------------");
}