Is Operator Keyword In C#

expression is type

using System;

class Employee {

	// the data numbers
	public string name;
	public int id;

	//The methods of the other class
	public void details(string na, int rs)
	{
		name = na;
		id = rs;
	}
}

class Dep {

	// the data members
	public int depnum;
	public int num;

	//The methods of dep
	public void count(int a1, int i1)
	{
		depnum = a1;
		num = i1;
	}
}

public class IsOperator {

	// Main method
	static public void Main()
	{

		// object creation 
		Employee a1 = new Employee();

		a1.details("Likith", 51);

		Dep d= new Dep();

		d.count(20, 30);

		bool res;
        // Use the is operator to determine 
        //whether 'a' is of the Employee type.
		res = a1 is Employee;
		Console.WriteLine("Is a is Employee? : {0}", res);

	
		res = d is Employee;
		Console.WriteLine("Is d is a Employee? : {0}", res);

		// a1 value as null
		a1 = null;

		// the null object
		res = a1 is Employee;
		Console.WriteLine("Is a is Employee? : {0}", res);
	}
}

Is a is Employee? : True
Is d is a Employee? : False
Is a is Employee? : False

using System;

// taking a class
public class Isop1{
	
}

// the derived class
public class Isop2 : Isop1 {
	
}

// the class Isop3
public class Isop3 {
	
}


// Driver Class
public class IsOperator{
	
	// Main Method
	public static void Main()
	{
		// creating the instance of the class Isop1
		Isop1 ob1 = new Isop1();
		
		// instance creation for ISop2
		Isop2 ob2 = new Isop2();
		
		// checking whether the object belongs to class Isop1
		Console.WriteLine(ob1 is Isop1);
		
		// // Checking if 'ob1' is an Object 
		//class (the fundamental class for all classes).
		Console.WriteLine(ob1 is Object);
		
		// checking whether the object ob2 is belongs to class Isop2
		Console.WriteLine(ob2 is Isop2);
		
		//Checking if 'ob2' is an Object 
		//class (the fundamental class for all classes).
		Console.WriteLine(ob2 is Object);
		
		//Checking if 'ob2' is of type 'Isop1' 
                       //will return true because Isop2 is derived    from Isop1.
		Console.WriteLine(ob2 is Isop1);
		
		//verifying whether object ob1 is of type Isop3, it is going to return false
		Console.WriteLine(ob1 is Isop3);
		
		// Evaluating if ob2 is of type Isop3 
		//will result in false.
		Console.WriteLine(ob2 is Isop3);
		
		
	}
}

True
True
True
True
True
False
False