public static void Main(string[] args)
{
// Object
Being b=new Being();
Console.WriteLine (b);
// Object attributes
Person p1=new Person();
p1.name="Jane";
Person p2=new Person();
p2.name="Beky";
Console.WriteLine (p1.name);
Console.WriteLine (p2.name);
// Methods
Circle c=new Circle();
c.SetRadius(5);
Console.WriteLine (c.Area());
// Access modifiers
Person2 p=new Person2();
p.name="Jane";
p.SetAge(17);
Console.WriteLine ("{0} is {1} years old",p.name,p.GetAge());
// another example of access modifiers
Derived d=new Derived();
d.info();
// The constructor
new Being2();
new Being2("Tom");
// another example of constructor
string name="Lenka";
DateTime born=new DateTime(1990,3,5);
MyFriend f=new MyFriend(name,born);
f.info();
// Constructor chaining
new Circle2(5);
new Circle2();
// Class constants
Console.WriteLine (Math.PI);
Console.WriteLine (Math.radius);
// The ToString() method
Being3 be=new Being3();
object ob=new object();
Console.WriteLine (ob.ToString());
Console.WriteLine (be.ToString());
Console.WriteLine (be);
// Note that when we call the Console.WriteLine() method
// with an object as a parameter,
// the ToString() is being called.
// Inheritance
new Human();
// another example
Console.WriteLine ();
new Human2();
Dog dog=new Dog();
dog.GetCount();
// another example2
Console.WriteLine ();
Circle3 x=new Circle3(2,4,6);
Console.WriteLine (x);
// Abstract classes and methods
Console.WriteLine ();
Circle4 z=new Circle4(12,45,22);
Console.WriteLine (z);//show the ToString() method, defaultly
Console.WriteLine ("Area of circle: {0}",z.Area());
Console.WriteLine (z.GetCoordinates());
}