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Why should you declare a destructor as virtual?
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.
Why destructor should be declared as virtual explain with a small example?
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.
Can destructor be declared as virtual?
Destructors in the Base class can be Virtual. Whenever Upcasting is done, Destructors of the Base class must be made virtual for proper destrucstion of the object when the program exits. NOTE: Constructors are never Virtual, only Destructors can be Virtual.
What is a virtual destructor explain with an example?
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.
Why are there no virtual constructors?
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.
Can constructors be private?
Yes. Class can have private constructor. Even abstract class can have private constructor. By making constructor private, we prevent the class from being instantiated as well as subclassing of that class.
Why is destructor always declared virtual?
Declaring the base class destructor as virtual ensures the call of the derived class destructor, when an object of the derived class type is destroyed via a pointer or a reference of the base class type.
Why are Constructors Cant be virtual?
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. So, the constructor should always be non-virtual.
Why can’t constructor be virtual?
The reason why constructor can’t be virtual is that the virtual mechanism will work only on completely constructed objects. At the time when the constructor get called, the object is not completely created. So there cannot be virtual constructors.
Why is the destructor not called?
The destructor is not being called because terminate () for the unhandled exception is called before the stack gets unwound. The specific details of what the C++ spec says is outside of my knowledge, but a debug trace with gdb and g++ seems to bear this out.
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