C# internal Access Specifiers,

Question

I have Created one ConsoleApplication to understand Access Specifiers.

Below is my code for internal, I can access this class from outside the Assembly.

namespace Assembly_1 //This is first assembly.
{       
   public class Base
   {
       //internal class
       internal class B
       {
          public static void fnB()
          {
            Console.WriteLine("fnB");
          }
       }        
   }    
}

namespace Assembly_2 //This is second assembly.
{   
    public class Derived : Assembly_1.Base
    {            
        public class D
        {
            public void fnD()
            {
                B.fnB();//how can I access this class?
            }
        }
    }
}

And this is where I am Accessing it.

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {                
            Assembly_2.Derived.D d = new Assembly_2.Derived.D();
            d.fnD();
        }
    }
}

My Question

Right now I can Access Class B and it's methods like fnB() in Derived.

Everything works fine. but How?

How can I access the B Class outside Assembly_1?

Answer 1

As I worte in the comments:

You are confusing the namespace and assembly terms. You can read about it here:(Assemblies and Namespace)

Many namespaces can be defined in a single assembly.

If you would like to check and understand the internal modifier, then you would have to create a new class library project (that will compile into a different assembly), define the Base class there and add a reference to it in your main console application. Then you will see that you don't have access to it anymore and the code will not compile.

Answer 2

How can I access the B Class outside Assembly_1?

Because you're confusing namespaces and assemblies. An assembly is a collection of one or more namespaces, contained within a .dll or .exe file.

See also: MSDN: Assemblies in the Common Language Runtime and Understanding and Using Assemblies and Namespaces in .NET.

What you call Assembly_1 and Assembly_2 are namespaces within the same assembly.

Because internal members are visible within the same assembly, you can use Assembly_1.B from Assembly_2.D, because both namespaces reside in the same assembly.