Access Specifiers

Access Specifiers – these are also modifiers used to define scope of a type (Class or Interface or Structure) as well as their members i.e. who can access them and who cannot.

C# has 5 different Specifiers those are

• Private
• Internal
• Protected
• Protected Internal
• Public

Note – Members define in a type with any Specifiers (Scope) are always accessible within the type, all the restrictions comes in to the picture only when we try to access them outside of the type.

• Private – Members declared as private under class or structure is not accessible outside of them in which they are defining. Default scope for members of a class and structure is private, but public in the case of interface. Interface cannot contain private member in it. A type can never be declared as private.
• Protected – Members declared as protected under a class or interface can be accessed only from its children or within itself , an non – child class cannot consumed .Types cannot be declared as protected also.

Q – How to restrict a class not to be accessible from any other class?

Ans – This can be done by declaring constructors of classes private    

Q – How to restrict a class not to be inherited for any other class?

Ans – This can be done by declaring class as Sealed.

Q – How to restrict a class not to be accessible for any other class to consume by creating its object?

Ans – This can be done by declaring constructor of a class is Private.

•  Internal - Members of types that are declared as internal are accessible only within the project both from child or non-child class the default Scope for only type in C# is internal only.
• Protected internal – Members declared as Protected Internal enjoy dual scope i.e. within the project they behave as Internal providing access to others, outside the project they change protect and still provide access to child classes.
• Publicu - A type or member of a type if declared as Public is global in scope that can be access from anywhere.

  Cases	Private	Internal	Protected	Protected Internal	Public
  case 1					
  case 2	X				
  case 3	X		X		
  case 4	X	X			
  case 5	X	X	X	X	

Case 1 – Accessing members with in the same class. 

Case 2 - Accessing members with in child class of same project. 

Case 3 - Accessing members with in non-child class of same project

Case 4 - Accessing members with in child class of other project.

Case 5 - Accessing members with in non-child class of other project.