Can we call virtual function in destructor in C++?
Yes. Calling a virtual function from a constructor or destructor dispatches the function as if the object’s dynamic type were that currently being constructed or destroyed.
Can you use virtual functions in constructors and destructors?
A C++ constructor calls a virtual function. As a general rule, you should never call virtual functions in constructors or destructors. If you do, those calls will never go to a more derived class than the currently executing constructor or destructor.
What are virtual functions in C++?
A C++ virtual function is a member function in the base class that you redefine in a derived class. It is declared using the virtual keyword. It is used to tell the compiler to perform dynamic linkage or late binding on the function.
Do not invoke virtual functions from constructors or destructors?
Calling virtual functions from a constructor or destructor is considered dangerous most of the times and must be avoided whenever possible. All the C++ implementations need to call the version of the function defined at the level of the hierarchy in the current constructor and not further.
Can destructor be virtual?
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.
When should a 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 destructor C++?
Destructors in C++ are members functions in a class that delete an object. They are called when the class object goes out of scope such as when the function ends, the program ends, a delete variable is called etc. Also, destructors have the same name as their class and their name is preceded by a tilde(~).
Which of the following can not be declare as virtual in C++? constructor destructor function friend function?
2. Which of the following cannot be used with the virtual keyword? Explanation: Virtual keyword cannot be used with constructors as constructors are defined to initialized an object of particular class hence no other class needs constructor of other class.
Can we have virtual destructor?
What is the purpose of 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.
What is the purpose of virtual destructor in C++ Mcq?
Q) What is purpose of Virtual destructor? To maintain the call hierarchy of destructors of base and derived classes. Destructor can be virtual so that we can override the destructor of base class in derived class.
Why do we use virtual destructor?
Virtual destructors in C++ are used to avoid memory leaks especially when your class contains unmanaged code, i.e., contains pointers or object handles to files, databases or other external objects. A destructor can be virtual.
What is virtual destructor in C++?
Virtual Destructor. Deleting a derived class object using a pointer to a base class that has a non-virtual destructor results in undefined behavior. To correct this situation, the base class should be defined with a virtual destructor.
How to declare a destructor as a pure virtual function?
What you have commented out is a pure-virtual declaration for a destructor. That means the function must be overridden in a derived class to be able to instantiate an object of that class. What you want is just a definition of the destructor as a virtual function: virtual ~Media() {}
How to fix “deleting a derived class with a non-virtual destructor”?
Deleting a derived class object using a pointer of base class type that has a non-virtual destructor results in undefined behavior. To correct this situation, the base class should be defined with a virtual destructor. For example, following program results in undefined behavior.
Are pure virtual destructors legal in C++?
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. You may be wondering why a pure virtual function requires a function body.