ACCESS SPECIFIER (ACCESS MODIFIER)

Access Specifier(Access Modifier)  are keywords in object oriented programming,which specify accessibility of Types and Types Members. 

Remember these points:

• By default Members of classes are  Private  .
• By default Classes  are Internal.
• By default Namespaces are Public but we are not supposed to specify public keyword.                                                 

Access Specifier are as follows:

1.Private -Members can be accessed within the class only                                                                                
********************Example 1********************************                                                     namespace Sample

{

   public class ABC

   {

       private int Id;

   }

 

    public class Program

   {

        public static void Main(string[] args)

        {

            ABC abc = new ABC();

            abc.Id = 10;//Error ,Id is private

        }

   }

}

// Output :Error 1 ‘Sample.ABC.Id’ is inaccessible due to its protection level 

2.Public- As name says members can be accessed from any class and any assembly.  

3:Protected-Members can be accessed within its class and derived class of same assembly
Protected members are also accessible outside assembly provided it should be derived 

.********************Example1********************************  

namespace Sample

{

   public class ABC

   {

       protected int Id;

   }

 

    public class Program

   {

        public static void Main(string[] args)

        {

            ABC abc = new ABC();

            abc.Id = 10;//error ,its protected

        }

   }

}

// Output :Error 1 ‘Sample.ABC.Id’ is inaccessible due to its protection level

********************Example2********************************

namespace Sample

{

    public class ABC

    {

        protected int Id;

    }

    public class XYZ : ABC

    {

        public void Print()

        {

            Id = 5;

            Console.WriteLine(Id);

        }

    }

    public class Program

    {

        public static void Main(string[] args)

        {

            XYZ xyz = new XYZ();

            xyz.Print();

            Console.ReadLine();

        }

    }

// Output : 5   

4:Internal- Members can be accessed only within the same assembly.      

Create a Class library

namespace ClassLibrary1

{

    public class Class1

    {

        internal int a;

    }

}

Now create a console application, take a reference of above library   

namespace Sample

{ 

    public class Program

   {

        public static void Main(string[] args)

        {

            ClassLibrary1.Class1 cls = new Class1();

            cls.a = 6; // error           

        }

   }

}

// Output  Error      1 'ClassLibrary1.Class1' does not contain a definition for 'a' and no extension method 'a' accepting a first argument of type 'ClassLibrary1.Class1' could be found (are you missing a using directive or an assembly reference?       

5:Protected Internal- Members can be accessed anywhere in same assembly and also accessible  by inheriting that class. It can be accessible outside assembly in derived class only. Protected Internal member works as Internal within the same assembly and works as Protected for outside the assembly.   

namespace ClassLibrary1

{

    public class Class1

    {

      protected internal int a;

    }

}

Now create a console application, take a reference of above library   

namespace Sample

{

   public class ABC:Class1

   {

       private int Id;

       public void XYZ()

       {

           a = 5;

           Console.WriteLine(a);

       }

   }

 

    public class Program

   {

        public static void Main(string[] args)

        {

            ABC abc = new ABC();

            abc.XYZ();

            Console.ReadKey();

          

        }

   }

}                     

// Output : 5