What is the use of virtual function in C++?

A virtual function allows derived classes to replace the implementation provided by the base class. The compiler makes sure the replacement is always called whenever the object in question is actually of the derived class, even if the object is accessed by a base pointer rather than a derived pointer.

What is friend function and its uses?

A friend function is used to access all the non-public members of a class. You can use a friend function to bridge two classes by operating objects of two different classes.

What is the purpose of friend function and friend class in C++?

A friend class in C++ can access the private and protected members of the class in which it is declared as a friend. A significant use of a friend class is for a part of a data structure, represented by a class, to provide access to the main class representing that data structure.

What is virtual function example?

A virtual function is a member function that you expect to be redefined in derived classes. When you refer to a derived class object using a pointer or a reference to the base class, you can call a virtual function for that object and execute the derived class’s version of the function.

What is pure virtual function in C++?

A pure virtual function is a virtual function in C++ for which we need not to write any function definition and only we have to declare it. It is declared by assigning 0 in the declaration. If an Abstract Class has derived class, they must implement all pure virtual functions, or else they will become Abstract too.

What are virtual base classes in C++?

Virtual base classes are used in virtual inheritance in a way of preventing multiple “instances” of a given class appearing in an inheritance hierarchy when using multiple inheritances.

What is virtual constructor in C++?

Virtual Constructor in C++ The virtual mechanism works only when we have a base class pointer to a derived class object. In C++, the constructor cannot be virtual, because when a constructor of a class is executed there is no virtual table in the memory, means no virtual pointer defined yet.

What is virtual function?

What is a virtual function in C++ Mcq?

Virtual functions are functions that can be overridden in derived class with the same signature.

What is virtual function and virtual class?

What is a friend function in C++?

The friend function definition is found outside the class like a normal member function. The friend function is not defined using the friend keyword or use the scope resolution operator :: as it is not a member of the class in which it has been declared. A friend function can be declared in several classes.

What is the difference between virtual and friend in C++?

Friend is totally unrelated to virtual. It is simply lets a function, or another class, assess the privates of this class. Usually, you don’t want to use friend, but sometimes this is the correct way to do things. For example: Here, the operator<< is a friend of Baz, so it can access data_, in order to print it.

What is virtual function in C++ with example?

Virtual Function in C++. A virtual function a member function which is declared within base class and is re-defined (Overriden) by derived class. When you refer to a derived class object using a pointer or a reference to the base class, you can call a virtual function for that object and execute the derived class’s version of the function.

Can We invoke a friend function from an object?

The function is not in the ‘scope’ of the class to which it has been declared a friend. Friend functions can be a member of a class or a function that is declared outside the scope of class. It cannot be invoked using the object as it is not in the scope of that class. We can invoke it like any normal function of the class.