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- Understanding C# Class and Member Modifiers
- How to: Control the Availability of a Variable
- Access Levels in Visual Basic
- Working with .NET access modifiers
Classes and their access modifiers
So let’s see what the differences are between the access modifiers of VB.Net and C#. I found this list.
For VB.Net that would be:
- Private
- Protected
- Friend
- Protected friend
- Public
In C# that will be:
- private
- protected
- internal
- protected internal
- public
So Friend becomes internal in C# and C# uses a different capitalization. That is a good thing to remember.
Now let’s see if they do the same thing.
Private or private
Let’s try something.
In C_Class_Library_2.
- using System;
- using System.Collections.Generic;
- using System.Linq;
- using System.Text;
- namespace C_Class_Library_2
- {
- private class Class1
- {
- }
- }
This gives me the error.
Elements defined in a namespace cannot be explicitly declared as private, protected, or protected internal
So I can’t do this. In C#, I had to build it before getting this error.
In VB_Class_Library_2.
- Private Class Class1
- End Class
Slightly different error.
Types declared ‘Private’ must be inside another type.
The VB.Net error seems to be more to the point. And I didn’t need to compile.
So lets use Private class for what it is intended.
In C_Class_Library_2.
- using System;
- using System.Collections.Generic;
- using System.Linq;
- using System.Text;
- namespace C_Class_Library_2
- {
- public class Class1
- {
- private class Class1_1
- {
- }
- }
- }
In VB_Class_Library_2
- Public Class Class1
- Private Class Class1_1
- End Class
- End Class
These private classes can only be used inside the class where they are declared.
So doing this in the consoleapp will not work.
In C_Console.
- using System;
- using System.Collections.Generic;
- using System.Linq;
- using System.Text;
- namespace C_Console
- {
- class Program
- {
- static void Main(string[] args)
- {
- C_Class_Library_2.Class1_1 class1 = new C_Class_Library_2.Class1_1();
- C_Class_Library_2.Class1.Class1_1 class2 = new C_Class_Library_2.Class1.Class1_1();
- }
- }
- }
The first line gives this error.
The type or namespace name ‘Class1_1′ does not exist in the namespace ‘C_Class_Library_2′ (are you missing an assembly reference?)
And the second line will give.
‘C_Class_Library_2.Class1.Class1_1′ is inaccessible due to its protection level
Now let’s do the same in VB.Net.
In VB_Console.
- Module Module1
- Sub Main()
- Dim class1 As New VB_Class_Library_2.Class1_1
- Dim class2 As New VB_Class_Library_2.Class1.Class1_1
- End Sub
- End Module
The first line gives this.
Type ‘VB_Class_Library_2.Class1_1′ is not defined.
The second line gives.
‘VB_Class_Library_2.Class1.Class1_1′ is not accessible in this context because it is ‘Private’.
Now lets see if we can return something of Class1_1.
In C_Class_Library_2
- using System;
- using System.Collections.Generic;
- using System.Linq;
- using System.Text;
- namespace C_Class_Library_2
- {
- public class Class1
- {
- public Class1_1 getClass1_1()
- {
- }
- private class Class1_1
- {
- }
- }
- }
After compilation we get this error message.
Inconsistent accessibility: return type ‘C_Class_Library_2.Class1.Class1_1′ is less accessible than method ‘C_Class_Library_2.Class1.getClass1_1()’
Which is very logical.
In VB_Class_Library_2.
- Public Class Class1
- Public Function GetClass1_1() As Class1_1
- End Function
- Private Class Class1_1
- End Class
- End Class
We get this error message.
‘GetClass1_1′ cannot expose type ‘Class1_1′ in namespace ‘VB_Class_Library_2′ through class ‘Class1′.
Seems fine by me.
Apart from a difference in wording, they seem to be both in agreement. I wish the two teams could sit together and get the error messages the same, preferably taking the good from both sides.
This post is long enough. I think I covered all the basics of private class. You might think this is too basic, but I learned something from it. I could have gone on and on with nesting, but I guess you get the point. Next up is protected or Protected.
