.NET has five access Specifiers

.Net has five access Specifiers

Public -- Accessible outside the class through object reference.

Private -- Accessible inside the class only through member functions.

Protected -- Just like private but Accessible in derived classes also through member 

functions.

Internal -- Visible inside the assembly. Accessible through objects.

Protected Internal -- Visible inside the assembly through objects and in derived classes outside the assembly through member functions.

Let’s try to understand by a practical example:-

public class Class1

    {

        int  i;                                         //No Access specifier means private

        public  int j;                                        // Public

        protected int k;                             //Protected data

        internal int m;                        // Internal means visible inside assembly

        protected internal int n;                   //inside assembly as well as to derived classes outside assembly

        static int x;                                 // This is also private

        public static int y;                       //Static means shared across objects

        [DllImport("MyDll.dll")]

        public static extern int MyFoo();       //extern means declared in this assembly defined in some other assembly

        public void myFoo2()

        {

            //Within a class if you create an object of same class then you can access all data members through object reference even private data too

            Class1 obj = new Class1();

            obj.i =10;   //Error can’t access private data through object.But here it is accessible.:)

            obj.j =10;

            obj.k=10;

            obj.m=10;

            obj.n=10;

       //     obj.s =10;  //Errror Static data can be accessed by class names only

            Class1.x = 10;

         //   obj.y = 10; //Errror Static data can be accessed by class names only

            Class1.y = 10;

        }

    }

Now lets try to copy the same code inside Main method and try to compile

[STAThread]

        static void Main()

        {

           //Access specifiers comes into picture only when you create object of class outside the class

            Class1 obj = new Class1();

       //     obj.i =10; //Error can’t access private data through object.

            obj.j =10;

      //      obj.k=10;     //Error can’t access protected data through object.

            obj.m=10;

            obj.n=10;

       //     obj.s =10;  //Errror Static data can be accessed by class names only

            Class1.x = 10;  //Error can’t access private data outside class

         //   obj.y = 10; //Errror Static data can be accessed by class names only

            Class1.y = 10;

        }

What if Main is inside another assembly

[STAThread]

        static void Main()

        {

           //Access specifiers comes into picture only when you create object of class outside the class

            Class1 obj = new Class1();

       //     obj.i =10; //Error can’t access private data through object.

            obj.j =10;

      //      obj.k=10;     //Error can’t access protected data through object.

     //     obj.m=10; // Error can’t access internal data outside assembly

    //      obj.n=10; // Error can’t access internal data outside assembly

       //     obj.s =10;  //Errror Static data can be accessed by class names only

            Class1.x = 10;  //Error can’t access private data outside class

         //   obj.y = 10; //Errror Static data can be accessed by class names only

            Class1.y = 10;

        }

In object-oriented software, complexity is managed by using abstraction.

Abstraction is a process that involves identifying the critical behavior of an object and eliminating irrelevant and complex details.