Access Specifiers in .NET

.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.

Inheritance:

Inheritance is a process of deriving the new class from already existing class

C# is a complete object oriented programming language. Inheritance is one of the primary concepts of object-oriented programming. It allows you to reuse existing code. Through effective use of inheritance, you can save lot of time in your programming and also reduce errors, which in turn will increase the quality of work and productivity. A simple example to understand inheritance in C#.