using System;

public class Program

{

    // A very simple class with a single property

    // Properties are variables you manipulate

    // A property with a "get" means you can use it on the right side of an equation, "set" means the left side

    //

    // note: this class has no "constructor" defined, 

    // which means the automatic/default constructor of "new MyClass()" is the only way to instantiate the class

    public class MyClass

    {

        public string MyProperty { get; set; }

    }

    public static void Main()

    {       

        MyClass myInstance1 = new MyClass(); // uses the automatic/default constructor

        myInstance1.MyProperty = "abcdef"; // instances can now get or set their properties - this is using the "set" functionality

        /* Properties are cool

           If you are using the automatic/default constructor, 

           you can use the following syntax to instantiate with a property value in a single line of code

           note: that it uses curly braces not parens

         */

        MyClass myInstance2 = new MyClass { MyProperty = "abcdef" };

        /* (myInstance1.MyProperty == myInstance2.MyProperty) is True

           however

           (myInstance1 == myInstance) is False

           you can and should test this out

           now if I do the following...

         */

        MyClass myInstance3 = myInstance1;

        /* note that I do not have to use the constructor at all!

           this is because when you declare an instance of a class (MyClass myInstance3), 

           the initialization (use of the equal sign) value can be another instance of the same class

           and further,

           (myInstance1 == myInstance3) is True

           hrrmmmm...you should be asking yourself why is

           (myInstance1 == myInstance3) is True

           and

           (myInstance1 == myInstance2) is False

           yet

           (all the MyProperty comparisons would be true between all three instances

           the answer lies in understanding that there are really only TWO instances in memory

           let me explain...

           when you compare an integer, string (or similar) to another - those are values (because they are primitive types)

           when you compare an instance of a class - those are references (because they are object types)

           so when ask

           (myInstance1.MyProperty == myInstance2.MyProperty)

           you are asking - Does the value "abcdef" equal the value of "abcdef" - and the answer is Yes

           but when you ask

           (myInstance1 == myInstance2)

           you are asking - Does is the address in memory consumed by myInstance1 the same address in memory consumed by myInstance2 - and the answer is No

           they are in two different places in the memory stack; change the myInstance1.MyProperty value and myInstance2.MyProperty is not changed

           and finally when you ask

           (myInstance1 == myInstance3)

           the answer is Yes, because when we initialized myInstance3 with "MyClass myInstance3 = myInstance1;"

           we were actually saying, make the address in memory of myInstance3 the same address in memory as myInstance1

           in other words, make them THE SAME THING, not the SAME VALUES

           See it in action below

         */

        Console.WriteLine("myInstance1.MyProperty is {0}", myInstance1.MyProperty);

        Console.WriteLine("myInstance2.MyProperty is {0}", myInstance2.MyProperty);

        Console.WriteLine("myInstance3.MyProperty is {0}", myInstance3.MyProperty);

        myInstance1.MyProperty = "vwxyz";

        Console.WriteLine("myInstance1.MyProperty is {0}", myInstance1.MyProperty);

        Console.WriteLine("myInstance2.MyProperty is {0}", myInstance2.MyProperty);

        Console.WriteLine("myInstance3.MyProperty is {0} (Why did this change?)", myInstance3.MyProperty);  

    }

}