For example if u define a method as:

protected internal void DoSomething()
{
Console.WriteLine(“I’m Doing…”);
}

Normally, you think this method is protected and internal!!!! <—- THIS IS WRONG !!!!!

The connection between them is OR = protected internal means protected OR internal

Example for that if you define an internal property and you try to set the setter or the getter as protected internal you will get a restrictive error because The union of protected and internal accessibility is less restrictive than protected or internal alone.

1. Actually I was wrong because you can’t cast A to A3.

2. I misinterpret your comment. What I meant is that class A3 can access SomeProtectedInternalMethod of class A because SomeProtectedInternalMethod is internal in class A and A3 is in the same assembly. But you made class A3 internal too, and it sounds like you are saying THIS is the reason why it can access the method. But you are not.

1. You are correct that we don’t have to inherit A3 from A to be able access SomeProtectedInternalMethod from the same assembly (thanks for noticing, probably just mistyped it), but you are wrong about using ((A3)AI).SomeProtectedInternalMethod() within or outside of an assembly in which class A is declared. You indeed can use it using casting but in the SAME assembly only.

2. You can’t access a method in some class just because the class is in the same assembly.
For example if the method was defined as “protected string SomeProtectedInternalMethod()” or just “string SomeProtectedInternalMethod()” you wouldn’t be able to access it even in the same assembly because in case of protected you must inherit the class and in the second case it’s just private for the same class.

Class A3 don’t have to inherit from A in your example. If it does, then you can access protected members even on another instance, like this:

A AI = new A();
return ((A3)AI).SomeProtectedInternalMethod();

Within or outside of an assembly in which class A is declared.

2. // We can access the method through an instance
// of the class because it’s internal

Not exactly right. We can access it just because it is in the same assembly.

The point is that you don’t need to declare class A3 as internal (as you did), this has absolutely nothing to do with the access to class A internal members.

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