Access Modifiers And Default Access Modifiers In C#

So far we have concluded that any element in namespace level is either public or internal. However, we have not yet reached any concrete statement yet.

However, let’s see outside “CheckAccessModifiers” assembly if we are able to access the Namespace level elements.

Steps:

1. We have created two classes named MyCustomClass and MyCustomClass1 in namespace “CheckAccessModifiers”.
2. Build the project. Create one more console project (in our example it is OutSideAssembly) at solution level.
3. Add a reference of “OutSideAssembly” to “CheckAccessModifiers”.
4. Include the namespace (using CheckAccessModifier)
5. In Main () method try to access the elements of “CheckAccessModifiers” Namespace.
   

Let’s see the below example. Here we have created another class named MyCustomClass1 and tried to access the members of MyCustomClass.

We are only able to see “MyCustomClass1”.

Findings

The reference table from MSDN says, internal is only accessible in current assembly. Public modifiers can be accessed anywhere. If we recall it properly in our very first example, we saw elements at Namespace level can either be public or internal.

We had two classes named MyCustomClass and MyCustomClass1. The type of access modifiers they hold is unknown/default and public. Since at name space level we cannot use private/protected internal/protected.

MyCustomClass1 is accessible in namespace “OutSideAssembly” since it is declared as public, which means the default access modifier in C# at Namespace level element is “Internal”.

Implementation at Class Level and Function Level

To understand this concept, we have created three classes withinthe namespace “CheckAccessModifiers.” Currently, MyCustomClass is holding some data members of different access levels. MyCustomClass2 is inheriting from MyCustomClass.

We end up with two scenarios again. First we will check the behavior of the data members available in MyCustomClass within same namespace but inside different classes.

Scenario 1: (Within Namespace, outside class- In our case it is MyCustomClass1)

After creating the object, we can see only fifthNumber, firstNumber and fouthNumber is available to us.

I.e. only members having modifiers either public/protected internal/internal is accessible in other classes.

Scenario 2: (Within Namespace, outside class inheriting from base class- in our case it is MyCustomClass2).

We are again having access to fifth, first, fourth and third variable. I.e. only members having modifiers either public/protected internal/internal/Protected is accessible in other classes.

Now we end up with a question, if public/protected internal/internal is available anywhere in the namespace how do we choose the appropriate access modifier at class level?

Let’s check the behavior outside the Namespace. We will follow to same steps and go to Namespace “OutSideAssembly”.

Below is the structure of classes in “OutSideAssembly” Assembly.

We have two more classes named Program and MyCustomClass3. MyCustomClass3 is inheriting from MyCustomClass. Our intention is to check the availability of data members outside the namespace.

Inside program class, when we try to access the following, is output.

Only firstNumber variable is available. This justifies the definition that public members have no restriction at all.

Let’s see the behavior inside MyCustomClass3.

We are able to access first, fifth, and third variable.

On derived class examples whether it is within the namespace or outside the namespace, we saw that members with accessibility protected and protected internal is available in derived class.

Then how to choose when to Choose Protected and when to choose protected internal?

Solution

Friends this part is bit interesting, when we want any member to be available only in derived class within the same assembly but not to a normal class in other assembly, then one should go with Protected; however, if one is looking for a member which will be available anywhere in the current assembly but only in derived class in the outside namespace then one should choose protected internal.

Conclusion

Default access modifiers at Namespace level are internal.

Default access modifiers at Class level are private.

Default access modifiers at function level are private; we are not allowed to use even private keywords explicitly.

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