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What else can I help you with?
Can a friend function of derived class access private data of base class?
In some computer languages it is possible to do so, but I would not even think or design any application in this way. A base class SHOULD NEVER know what the derived classes are. Perhaps it was created by generalizing some classes. Even at that point, this new base class should have no knowledge of the derived classes whatsoever. To do a good OO design, the base class should have a method like getPrivatePartOfDerivedClass() as abstract, then force the derived class to provide the implementation of this method.
What do you mean by protected derivation of a sub class from base class?
When you derive a class (the sub-class) from a base class using protected access, all public members of the base class become protected members of the derived class, while protected members of the base class will remain protected. Private members are never inherited so they remain private to the base class. By contrast, if you use public inheritance, the public members of the base class remain public to the derived class, while protected members of the base class remain protected in the derived class. If you use private inheritance, both the public and protected members of the base class become private to the derived class. Note that accessibility cannot be increased, only reduced or left the same. That is, a protected member of a base class cannot be inherited as a public member of a derived class -- it can only be declared private or remain protected. Note also that accessibility is viewed from outside of the derived class. That is, all members of a base class other than the private members are inherited by the derived class and are therefore fully accessible to the derived class. But from outside of the derived class, all base class accessibility is determined by the access specified by the type of inheritance.
What is the application of public protected and private keywords?
The public, protected, and private keywords are access modifiers that specify if the item they modify can be accessed inside or outside the class or a derived class.A public item is fully accessible, inside or outside the class, including inside a derived class.A protected item is accessible only inside the class or inside a derived class.A private item is accessible only inside the class.
What is a public class?
A public class is a base class declared with public inheritance: class base { // ... }; class derived : public base { // ... }; In the above example, base is a public class of derived, thus derived is regarded as being a type of base. The derived class inherits all the public and protected methods of its base. Protected methods are accessible to the derived class, its derivatives and their friends. If base were declared protected, its public methods become protected methods of derived. The base class is then an implementation detail of derived; only members of derived, its derivatives and their friends can treat derived as being a type of base. If declared private, the public and protected methods of base become private methods of derived. The base class is then an implementation detail of derived; only members of derived and its friends can treat derived as a type of base.
Which base class member functions are not inherited by a derived class?
Derived classes only inherit the protected and public members of their base classes. Private member functions cannot be inherited by a derived class.
Can a friend function of derived class access private data of base class?
In some computer languages it is possible to do so, but I would not even think or design any application in this way. A base class SHOULD NEVER know what the derived classes are. Perhaps it was created by generalizing some classes. Even at that point, this new base class should have no knowledge of the derived classes whatsoever. To do a good OO design, the base class should have a method like getPrivatePartOfDerivedClass() as abstract, then force the derived class to provide the implementation of this method.
What do you mean by protected derivation of a sub class from base class?
When you derive a class (the sub-class) from a base class using protected access, all public members of the base class become protected members of the derived class, while protected members of the base class will remain protected. Private members are never inherited so they remain private to the base class. By contrast, if you use public inheritance, the public members of the base class remain public to the derived class, while protected members of the base class remain protected in the derived class. If you use private inheritance, both the public and protected members of the base class become private to the derived class. Note that accessibility cannot be increased, only reduced or left the same. That is, a protected member of a base class cannot be inherited as a public member of a derived class -- it can only be declared private or remain protected. Note also that accessibility is viewed from outside of the derived class. That is, all members of a base class other than the private members are inherited by the derived class and are therefore fully accessible to the derived class. But from outside of the derived class, all base class accessibility is determined by the access specified by the type of inheritance.
What is the application of public protected and private keywords?
The public, protected, and private keywords are access modifiers that specify if the item they modify can be accessed inside or outside the class or a derived class.A public item is fully accessible, inside or outside the class, including inside a derived class.A protected item is accessible only inside the class or inside a derived class.A private item is accessible only inside the class.
What are Public and Private inheritance in c plus plus?
Public, protected and private inheritance determine how the public and protected base class members are inherited by the derived class. Private members are never inherited and are therefore unaffected by the type of inheritance (they remain private to the base class). The following table summarises how inheritance affects accessibility of base class members with respect to the derived class: public inheritanceprotected inheritanceprivate inheritancepublic member of base classpublic member of derived classprotected member of derived classprivate member of derived classprotected member of base classprotected member of derived classprotected member of derived classprivate member of derived classprivate member of base classprivate member of base classprivate member of base classprivate member of base class Note that accessibility to individual public and protected base class members can be overridden within the derived class, regardless of the type of inheritance specified.
How can a base class protect derived classes so that changes to the base class will not affect them explain with example?
In order for a base class to protect derived classes, so that changes to the base class do not affect the derived classes, you must make sure that the public interface exposed by the base class does not change when the implementation of those public methods do change. You can also prevent inadvertant access to the base class attributes from the derived class, by making them private. class base { public: base(...) {...}; /* constructor */ base~(...) {...}; /* destructor */ method(...) {...}; /* other public methods */ private: ... etc. } class child : base { public: ... private: ... } So long as the calling sequence and functionality (interface) of the base class public methods do not change, the implementation of those public methods can change, and the private methods and attributes can change, without impacting any child class.
What is a public class?
A public class is a base class declared with public inheritance: class base { // ... }; class derived : public base { // ... }; In the above example, base is a public class of derived, thus derived is regarded as being a type of base. The derived class inherits all the public and protected methods of its base. Protected methods are accessible to the derived class, its derivatives and their friends. If base were declared protected, its public methods become protected methods of derived. The base class is then an implementation detail of derived; only members of derived, its derivatives and their friends can treat derived as being a type of base. If declared private, the public and protected methods of base become private methods of derived. The base class is then an implementation detail of derived; only members of derived and its friends can treat derived as a type of base.
What is public derivation in object-oriented programming?
Public derivation or public inheritance means that all the public members of the base calls are declared public in the derived class while the protected members remain protected. Protected inheritance means all the public members of the base class are declared protected in the derived class, as are the protected members. Private inheritance means all the public and protected members of the base class are declared private in the derived class. Private members of the base class are never inherited and are therefore unaffected by inheritance. Note that regardless of the type of inheritance specified, individual non-private members of the base class can be inherited with public or protected access as required of the derived class. The type of inheritance can be therefore be thought of as being the default inheritance for all base class members which can (optionally) be overridden for specific members where required.
Which base class member functions are not inherited by a derived class?
Derived classes only inherit the protected and public members of their base classes. Private member functions cannot be inherited by a derived class.
Is it true that a derived class inherits all the members of its base class?
False. A derived class inherits the public and protected members of its base class. Private members of the base class cannot be inherited.
Give an example of constructor and destructor in derived class?
class superclass { public: superclass() {... } // c'tor public: virtual ~superclass() {... } // d'tor }; // superclass class derived: public superclass { public: derived() : superclass() { ... } // derived c'tor public: virtual ~derived() {... } // derived d'tor }; // derived class
Difference bitween various visibility modes used c plus plus?
By visibility I assume you mean member accessibility. C++ uses three levels of accessibility: private, protected and public. Private members are only accessible to the class itself and friends of the class. Protected members are the same as private members except derived classes also have access. Public members are fully accessible. With regards inheritance, base class members with greater access than that specified are reduced to the specified access in the derived class. Thus public inheritance has no effect on base class member access. Protected inheritance reduces public members of the base class to protected members of the derived class. Private inheritance reduces both public and protected members of the base class to private members of the derived class. Private members of the base class are never inherited, thus they always remain private to the base class. Note that access to base class members can never be increased through inheritance, only reduced or kept the same. However, as well as defining an overall inheritance access, you can also specify member-wise inheritance access. Thus you could use public inheritance overall, but specify certain public members of the base class to be protected or private in the derived class and/or certain protected members of the base class to be private members of the derived class.
Which is public to all access class or struct or function or variable?
The default access specifier for a class is private. The default access specifier for a struct is public. It does not matter if it is a function or a variable.
