C# Access Specifiers

C# Access Specifiers

C# is an object-oriented programming language that includes various types, such as classes, structs, interfaces, enums, strings, arrays, and collections. These types have accessibility or visibility levels, determining whether they can be used within the same project or outside it. Each type has different members, such as properties, methods, constructors, indexers, and fields. In the case of classes, the accessibility of both the class itself and its members is determined by access modifiers.

To define accessibility, C# provides several modifiers, such as public, private, protected, internal, and protected internal. These modifiers determine the visibility of a type or its members.

Class Accessibility in C#

There are only two access modifiers available for classes: internal and public.

Class visibility refers to whether a class is accessible within its own project or from other projects. The visibility of a class is determined by its access modifier. By default, C# classes are internal.

Types of Class Accessibility:

1. Internal Class
   An internal class is accessible throughout the project in which it is defined but is not visible to any other project.
2. Public Class
   A public class is accessible within its own project and in any other project that references it. This makes the class consumable by any project.

By default, if no access modifier is specified, a class is internal. Other modifiers, such as private and protected, cannot be applied to top-level classes.

The usability of a class depends on its visibility. If a class is accessible, it can be used by other classes in the project. However, there is one exception: if an internal class has a private constructor, it cannot be instantiated by other classes within the project.

Class Member Accessibility

For member functions or methods of a class, C# provides five access modifiers:

1. Public
   A public method can be accessed by any class, regardless of whether the class is in the same project or another project.
2. Private
   A private method can only be accessed within the class in which it is defined. By default, methods in C# are private if no access modifier is specified.
3. Protected
   A protected method can be accessed by the class in which it is defined and by its derived (child) classes. This is possible due to inheritance, where child classes can access the non-private members of their parent class.
4. Internal
   An internal method is accessible by any class within the same project or assembly but is not visible to classes in other projects. This modifier essentially restricts access to the project in which the method is defined.
5. Protected Internal
   A protected internal method combines the features of both protected and internal access. Within the same project, it behaves like an internal method and can be accessed by any class. In an external project, it acts as a protected method and can only be accessed by the class itself or its derived classes.

Summary

• Classes in C# can only have internal or public access modifiers.
• By default, classes are internal unless explicitly marked as public.
• Members of a class can have public, private, protected, internal, or protected internal access modifiers, each offering a specific level of accessibility.

By understanding these access specifiers, developers can effectively control the visibility and accessibility of their code, ensuring better encapsulation and security.