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Can abstract class have protected members?
Yes, you can declare an abstract method protected. If you do so you can access it from the classes in the same package or from its subclasses. (Any you must to override an abstract method from the subclass and invoke it.)
Can you access private members of a base class?
Private members of a base class can only be accessed by base member functions (not derived classes). So you have no rights not even a chance to do so 🙂 Well, if you have access to base class, you can declare class B as friend class. Use protected members, if you want derived classes to be able to access them.
How are protected members of a base class?
If a class is derived privately from a base class, all protected base class members become private members of the derived class. Class A contains one protected data member, an integer i . Because B derives from A , the members of B have access to the protected member of A .
Why can’t abstract methods be private?
Private methods are not polymorphic (you cannot inherit them), so it makes no sense to make a private method abstract. Making a method abstract means you’d have to override and implement it in a subclass, but since you can’t override private methods, you can’t make them abstract either.
Can we declare abstract class as public?
Abstract classes are similar to interfaces. You cannot instantiate them, and they may contain a mix of methods declared with or without an implementation. However, with abstract classes, you can declare fields that are not static and final, and define public, protected, and private concrete methods.
Can I inherit the constructor and destructor of a base class?
The compiler automatically calls constructors when defining class objects and calls destructors when class objects go out of scope. Derived classes do not inherit or overload constructors or destructors from their base classes, but they do call the constructor and destructor of base classes.
Can we access protected member outside the package?
The protected access modifier is accessible within the package. However, it can also accessible outside the package but through inheritance only. We can’t assign protected to outer class and interface. If you make any constructor protected, you cannot create the instance of that class from outside the package.
How to access protected members in a derived class?
You can only access protected members in instances of your type (or derived from your type). You cannot access protected members of an instance of a parent or cousin type. In your case, the Derived class can only access the b member of a Derived instance, not of a different Base instance.
Do you have private members of an abstract base class?
If you use the Template Method design pattern (to implement the open/closed principle ), it is quite common to have private members of an abstract base class. As it stands, your example makes no sense.
What are abstract and sealed classes in C #?
Abstract and Sealed Classes and Class Members (C# Programming Guide) The abstract keyword enables you to create classes and class members that are incomplete and must be implemented in a derived class. The sealed keyword enables you to prevent the inheritance of a class or certain class members that were previously marked virtual.
Do you have to have protected members in C + +?
On the one hand C++ grants access to private/protected members for all instances of that class, but on the other hand it does not grant access to protected members of a base class for all instances of a subclass.