using System;

using System.Collections.Generic;

 namespace HashSetDemo

{

public class Program

{

    public static void Main()

    {

        HashSet<string> names=new HashSet<string>{"Rajeev", "Akash", "Amit"};

        foreach(var country in names)

        {

        Console.WriteLine(country);

        }

        names.Add("Rajeev");

        Console.WriteLine("---------");

        //duplicates are not added into collection.

        foreach(var name in names)

        {

        Console.WriteLine(name);

        }

        //ExceptWith 

        HashSet<string> names1=new HashSet<string>{"Rajeev", "Akash", "Amit","Deepak","Mohit"};

        names1.ExceptWith(names);

        Console.WriteLine("-----ExceptWith(elements not present in second(names)----");

        foreach(var name in names1)

        {

        Console.WriteLine(name);

        }

        //IntersectWith 

        names.IntersectWith(names1);

        Console.WriteLine("-----IntersectWith(elements common----");

        foreach(var name in names)

        {

        Console.WriteLine(name);

        }

        //UnionWith

        names.UnionWith(names1);

        Console.WriteLine("-----UnionWith----");

        foreach(var name in names)

        {

        Console.WriteLine(name);

        }

        Console.WriteLine("-----Custom HashSet With Duplicates----");

        HashSet<Employee> employees=new HashSet<Employee>

        {

            {new Employee{Emp_Id=1,Emp_name="Rajeev",Dept_name="IT"}},

            {new Employee{Emp_Id=1,Emp_name="Rajeev",Dept_name="IT"}},

            {new Employee{Emp_Id=3,Emp_name="Akash",Dept_name="IT"}},

            {new Employee{Emp_Id=4,Emp_name="Amit",Dept_name="IT"}}

        };

        Console.WriteLine("{0,-6}{1,10}{2,-8}","Emp_Id","Emp_name","Dept_name");

        Console.WriteLine("==============================");

        foreach(var employee in employees)

        {

            Console.WriteLine("{0,-8}{1,-10}{2,5}",employee.Emp_Id,employee.Emp_name,employee.Dept_name);

        }

        Console.WriteLine("==============================");

    }

}

     //Implement IEquatable Interface methods Equals and GetHashCode

     public class Employee:IEquatable<Employee>

    {

         public int Emp_Id{get;set;}

         public string Emp_name{get;set;}

         public string Dept_name{get;set;}

         public bool Equals(Employee other)

        {

                return this.Emp_Id.Equals(other.Emp_Id);

        }

​

        public override int GetHashCode()

        {

                return this.Emp_Id.GetHashCode();

        }

     }

}