C#: constructor of nested class makes "inaccessible due to protection level"

Question

I have this piece of code, and error is generated, just because I haved added into a constructor for its class.

class NestedClass
{
   class A
   {
      A() {}
   }

   class B
   {
       // no constructor
   }

   public static void run()
   {
     A a = new A();  // error
     B b = new B(); // no error
   }
}

And error is:

NestedExample.A is inaccessible due to protection level

Please help me explain this.

Thanks :)

score 7 · Answer 1 · answered Dec 28 '12 at 10:35

7

Your constructor is private. Default access modifier for class members is private.

   class A
   {
      A() {}
   }

this is correct implementation

   class A
   {
      public A() {}
   }

answered Dec 28 '12 at 10:35

Hamlet Hakobyan

32,965
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1

thanks. I come from java, so I think default for class members is public :D – hqt Dec 28 '12 at 10:39
2

@hqt, I think in Java the default is `package`, which is visible inside the package See [this](http://stackoverflow.com/questions/3530065/which-is-the-default-access-specifier-in-java) – Habib Dec 28 '12 at 10:47

Habib · Accepted Answer · 2012-12-28T10:40:37.070

Define your constructor as public

public A() { }

Your constructor for class A is private

Private Constructors (C# Programming Guide) - MSDN

Note that if you don't use an access modifier with the constructor it will still be private by default.

The reason it is working for B is that you haven't specified any constructor and for default constructor:

Constructor - MSDN

Unless the class is static, classes without constructors are given a public default constructor by the C# compiler in order to enable class instantiation

score 3 · Answer 3 · answered Dec 28 '12 at 10:35

3

Define the constructor as public

public class A
{
    public A() {}
}

answered Dec 28 '12 at 10:35

Rui Jarimba

11,166
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86

score 3 · Answer 4 · answered Dec 28 '12 at 10:36

3

Your constructor of A is private. It cannot be accessed from outside of A. At the same time, B does not have a consuctor at all and therefore gets a default public constructor.

answered Dec 28 '12 at 10:36

Ravi Y

4,296
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score 1 · Answer 5 · answered Dec 28 '12 at 10:37

1

you need to specify, the default one is private and while in the case of B the compiler provides a public parameterless constructor for you., so you have to specify it for class A

class A
{
    public A() { }
}

answered Dec 28 '12 at 10:37

V4Vendetta

37,194
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score 0 · Answer 6 · answered Dec 28 '12 at 10:36

0

Make your nested classes public and the problem will be solved. Your run method is public but the classes you want to use are not public and this gives problems.

answered Dec 28 '12 at 10:36

TimVK

1,146
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Indeed you are right about the constructor that just needs to be public. My mistake. – TimVK Dec 28 '12 at 10:47

C#: constructor of nested class makes "inaccessible due to protection level"

6 Answers6