Can Copy Constructor Be Virtual In C++?

Can we have virtual destructor 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..

Is copy constructor inherited C++?

Copy constructor is not inherited.

What is use of copy constructor in C++?

Copy constructor (C++) In the C++ programming language, a copy constructor is a special constructor for creating a new object as a copy of an existing object. Copy constructors are the standard way of copying objects in C++, as opposed to cloning, and have C++-specific nuances.

How do you write a derived class copy constructor?

class Base { protected: int m_nValue; public: Base(int nValue) : m_nValue(nValue) { } const char* GetName() { return “Base”; } int GetValue() { return m_nValue; } }; class Derived: public Base { public: Derived(int nValue) : Base(nValue) { } Derived( const Base &d ){ std::cout << "copy constructor\n"; } const char* ...

Why & is used in copy constructor?

That’s the reason for passing a reference to a copy constructor. It is necessary to pass object as reference and not by value because if you pass it by value its copy is constructed using the copy constructor. This means the copy constructor would call itself to make copy.

What is virtual base class with example?

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.

Can constructors be virtual in C++?

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.

Can a constructor be static?

No, we cannot define a static constructor in Java, If we are trying to define a constructor with the static keyword a compile-time error will occur. In general, static means class level. … We need to assign initial values for an instance variable we can use a constructor.

What is the default copy constructor C++?

A default constructor is a constructor which can be called without any arguments. A copy constructor is a constructor which can be called with a single argument of the same type. … This means that if you have a user defined copy constructor, the compiler will not implicitly declare a default constructor.

What is the benefit of copy constructor?

Copy constructors make it easy to copy objects. STL containers require all content to be copied and assigned. Copy constructors can be more efficient than copyfrom () solutions because they combine construction and replication.

When a copy constructor is called?

Copy constructor is called when a new object is created from an existing object, as a copy of the existing object. Assignment operator is called when an already initialized object is assigned a new value from another existing object.

Why do we need virtual destructors?

Virtual keyword for destructor is necessary when you want different destructors should follow proper order while objects is being deleted through base class pointer. for example: … If your base class destructor is NOT virtual then only base class object will get deleted(because pointer is of base class “Base *myObj”).

What is pure virtual function example?

A pure virtual function is a function that must be overridden in a derived class and need not be defined. A virtual function is declared to be “pure” using the curious =0 syntax. For example: class Base { … virtual void f3() = 0; // pure virtual.

Can we have pure virtual constructor?

Constructors cannot be virtual. You could go for two stage construction and provide a pure virtual Initialise() method that is called after the constructor.

Why do we need virtual destructor in C++?

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. … Now, suppose you create an instance of the Derived class using a Base class pointer.

What happens if destructor is not virtual?

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 do we use virtual function in C++?

A virtual function is a member function in the base class that we expect to redefine in derived classes. Basically, a virtual function is used in the base class in order to ensure that the function is overridden. This especially applies to cases where a pointer of base class points to an object of a derived class.