What is a virtual constructor?
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 destructor?
A virtual destructor is used to free up the memory space allocated by the derived class object or instance while deleting instances of the derived class using a base class pointer object.
Is virtual constructor possible?
Constructor can not be virtual, because when constructor of a class is executed there is no vtable in the memory, means no virtual pointer defined yet. Hence the constructor should always be non-virtual.
Is virtual destructor possible?
Yes, it is possible to have a pure virtual destructor. Pure virtual destructors are legal in standard C++ and one of the most important things to remember is that if a class contains a pure virtual destructor, it must provide a function body for the pure virtual destructor.
What are virtual functions give examples?
A virtual function is a member function that is declared within a base class and redefined by a derived class. To create virtual function, precede the function’s declaration in the base class with the keyword virtual.
When should destructor be virtual?
In particular, here’s when you need to make your destructor virtual:
- if someone will derive from your class,
- and if someone will say new Derived, where Derived is derived from your class,
- and if someone will say delete p, where the actual object’s type is Derived but the pointer p’s type is your class.
What is a pure virtual method?
A pure virtual function or pure virtual method is a virtual function that is required to be implemented by a derived class if the derived class is not abstract. Classes containing pure virtual methods are termed “abstract” and they cannot be instantiated directly.
What is virtual constructor in C#?
no, a class cannot have a virtual constructor. It doesn’t make sense to have a virtual constructor. The order in which objects are constructed in C# is by constructing derived classes first, so the derived constructor is always called since the class you want to call is well known at the time of construction.
Can virtual function friend?
A virtual function can be a friend function of another class. Virtual functions should be accessed using pointer or reference of base class type to achieve runtime polymorphism. The prototype of virtual functions should be the same in the base as well as derived class.
When should a destructor be virtual?
Can we have virtual destructor and pure virtual destructor?
Can a destructor be pure virtual in C++?
Can a destructor be pure virtual in C++? Yes, it is possible to have pure virtual destructor. Pure virtual destructors are legal in standard C++ and one of the most important things to remember is that if a class contains a pure virtual destructor, it must provide a function body for the pure virtual destructor.
What is a virtual constructor in C++?
Advanced C++ | Virtual Constructor. The User class is independent of object creation. It delegates that responsibility to Base, and provides an input in the form of ID. If the library adds new class Derived4, the library modifier will extend the if-else ladder inside Create to return proper object.
Can we make a class constructor virtual in C++ to create polymorphic objects?
Can we make a class constructor virtual in C++ to create polymorphic objects? No. C++ being statically typed (the purpose of RTTI is different) language, it is meaningless to the C++ compiler to create an object polymorphically.