C# Access Specifiers,C# Access Modifiers

Why to use access modifiers?
Access Modifiers (Access Specifiers) are keywords used to specify the declared accessibility of a member or a type. Access modifiers are an integral part of object-oriented programming. They support the concept of encapsulation, which promotes the idea of hiding functionality. Access modifiers allow you to define who does or doesn't have access to certain features.
C# provide five access specifiers , they are as follows 
1-public,
2-private ,
3-protected ,
4-internal 
5-and protected internal 
Here we will learn above access specifiers
1-public
It can be access from anywhere, that means there is no restriction on accessibility. The scope of the accessibility is inside class as well as outside. The type or member can be accessed by any other code in the same assembly or another assembly that references it.
Example: In the following example num1 is direct access.  

 using System;
   class Program
    {
        class AccessMod
        {
            public int num1;
        }

        static void Main(string[] args)
        {

            AccessMod ob1 = new AccessMod();

            //Direct access to public members

            ob1.num1 = 100;
            Console.WriteLine("Number one value in main {0}", ob1.num1);

            Console.ReadLine();

        }

    }
2-private 
Access is limited to within the class definition.struct in which they are declared. The private members cannot be accessed outside the class and it is the least permissive access level.

 Example: In the following example num2 is not accessible outside the class. 

using System;
    class Program
    {
        class AccessMod
        {
            public int number1;

            int number2;

        }

        static void Main(string[] args)
        {
            AccessMod ob1 = new AccessMod();
            //Direct access to public members

            ob1.a = 100;

            //Access to private member is not permitted
            ob1.number = 30;

            Console.WriteLine("Number one value in main {0}", ob1.a);

            Console.ReadLine();

        }

    }

 


























The above program will give compilation error, as access to private is not permissible. In the below figure you can see the private member number2 is not available. 
3-protected

Access is limited to within the class definition and any class that inherits from the class.

The type or member can be accessed only by code in the same class or struct, or in a class that is derived from that class.
Accessibility:

    Cannot be accessed by object
    By derived classes

using System;
class Program
 {
  class Base
   {
     protected int num1;
   }
   class Derived : Base
    {
      public int num2;
      static void Main(string[] args)
      {
        Base ob1 = new Base();
        Derived ob2 = new Derived();
        ob2.num1 = 20;
        // Access to protected member as it is inhertited by the Derived class
        ob2.num2 = 90;
        Console.WriteLine("Number2 value {0}", ob2.num2);
        Console.WriteLine("Number1 value which is protected {0}", ob2.num1);
        Console.ReadLine();

            }

        }

    }
In the above program we try to access protected member in main it is not available as shown in the picture below that num1 is not listed in intellisense.

4-internal

The internal access modifiers can access within the program that contain its declarations and also access within the same assembly level but not from another assembly.

Accessibility:

In same assembly (public)

    Can be accessed by objects of the class
    Can be accessed by derived classes

In other assembly (internal)

    Cannot be accessed by object
    Cannot be accessed by derived classes

5-protected internal 

Access is limited to within the class definition; This is the default access modifier type if none is formally specified.The type or member can be accessed by any code in the same assembly, but not from another assembly.A protected internal member is accessible from any class in the same assembly, including derived classes.The protected internal access modifier seems to be a confusing but is a union of protected and internal in terms of providing access but not restricting. It allows:

    Inherited types, even though they belong to a different assembly, have access to the protected internal members.
    Types that reside in the same assembly, even if they are not derived from the type, also have access to the protected internal members.

Default access
A default access level is used if no access modifier is specified in a member declaration. The following list defines the default access modifier for certain C# types:
enum: The default and only access modifier supported is public.

class: The default access for a class is private. It may be explicitly defined using any of the access modifiers.

interface: The default and only access modifier supported is public.

struct: The default access is private with public and internal supported as well.

The default access may suffice for a given situation, but you should specify the access modifier you want to use to ensure proper application behavior.