What are access modifiers? How many types of access modifiers are there in C++? Explain each one in detail and their role in implementing data hiding in object oriented programming.

Access Modifiers in C++

Access modifiers in C++ are keywords that control the visibility of class members (data members and member functions) to other parts of the program. They play a crucial role in implementing data hiding and encapsulation, which are fundamental principles of object-oriented programming.

C++ provides four types of access modifiers:

1. Public Access Modifier:

• The public access modifier allows members of a class to be accessed from anywhere within the program, including other classes, derived classes, and functions outside the class.
• Members declared as public can be directly accessed using the dot operator (.) from objects of the class.

   class MyClass
   {
   public:
       int public_data;
       void public_method() { }
   };

   int main() {
       MyClass object;
       object.public_data = 10; // Directly accessible
       object.public_method();   // Directly callable
       return 0;
   }

1. Protected Access Modifier:

• The protected access modifier allows members of a class to be accessed from within the class itself, as well as from derived classes (child classes).
• Protected members are not directly accessible from outside the class or from unrelated classes.

   class BaseClass
   {
   protected:
       int protected_data;
       void protected_method() { }
   };

   class DerivedClass : public BaseClass
   {
   public:
       void accessProtected() {
           protected_data = 10; // Accessible within derived class
           protected_method();    // Callable within derived class
       }
   };

   int main() {
       DerivedClass object;
       // Error: 'protected_data' is protected and cannot be accessed
       // object.protected_data = 10;

       // Error: 'protected_method' is protected and cannot be called
       // object.protected_method();

       object.accessProtected(); // Calls the 'accessProtected' method to access protected members
       return 0;
   }

1. Private Access Modifier:

• The private access modifier allows members of a class to be accessed only from within the class itself.
• Private members are not accessible from derived classes or from outside the class.

   class MyClass
   {
   private:
       int private_data;
       void private_method() { }
   };

   int main() {
       MyClass object;
       // Error: 'private_data' is private and cannot be accessed
       // object.private_data = 10;

       // Error: 'private_method' is private and cannot be called
       // object.private_method();

       return 0;
   }

1. Default Access Modifier (Implementation-Dependent):

• The default access modifier is implementation-dependent and varies across different compilers.
• In most implementations, the default access modifier is private, meaning that members declared without any explicit access modifier are treated as private.

Role of Access Modifiers in Implementing Data Hiding:

Data hiding is a fundamental principle of object-oriented programming that conceals the internal details and implementation of an object from the outside world. This helps to protect the integrity of the object's data and ensures that it is only modified in a controlled manner. Access modifiers play a crucial role in implementing data hiding by restricting the visibility of class members.

• Public Members: Public members are visible and accessible from anywhere within the program, including other classes, derived classes, and functions outside the class. This allows for easy access to the public interface of the class, enabling other parts of the program to interact with it.

• Protected Members: Protected members are visible and accessible within the class itself and its derived classes. This allows derived classes to access and modify the protected members of their base class, enabling the inheritance and extension of functionality. Protected members provide a balance between data hiding and the need for inheritance.

• Private Members: Private members are visible and accessible only within the class itself. This restricts access to the internal details of the class and prevents other parts of the program from directly modifying the private data. Private members enforce strong data hiding and encapsulation, ensuring that the internal state of the object is protected from unintended modifications.

In summary, access modifiers in C++ are essential for implementing data hiding and encapsulation in object-oriented programming. By controlling the visibility of class members, access modifiers allow developers to create well-defined interfaces, protect sensitive data, and promote modularity and code reusability.