Can virtual functions have a return type?

Yes. The return types are allowed to be different as long as they are covariant.

What is covariant return type in C++?

In object-oriented programming, a covariant return type of a method is one that can be replaced by a “narrower” type when the method is overridden in a subclass. This usually implies that the return types of the overriding methods will be subtypes of the return type of the overridden method.

What is virtual return type?

The return type of an overriding virtual function may differ from the return type of the overridden virtual function. The function B::f returns a pointer or a reference to a class of type T , and A::f returns a pointer or a reference to an unambiguous direct or indirect base class of T .

Can Constexpr be virtual?

You can now create a vector in constexpr code, insert some Derived class instances into it, and pass that to a constexpr function to operate on. So C++20 allows virtual functions to be declared constexpr .

How virtual functions are implemented C++?

To implement virtual functions, C++ uses a special form of late binding known as the virtual table. The virtual table is a lookup table of functions used to resolve function calls in a dynamic/late binding manner. A virtual table contains one entry for each virtual function that can be called by objects of the class.

Do virtual methods have to be overridden C++?

The virtual keyword can be used when declaring overriding functions in a derived class, but it is unnecessary; overrides of virtual functions are always virtual. Virtual functions in a base class must be defined unless they are declared using the pure-specifier.

How is covariant return types implemented?

How is Covariant return types implemented? Java doesn’t allow the return type-based overloading, but JVM always allows return type-based overloading. JVM uses the full signature of a method for lookup/resolution. Full signature means it includes return type in addition to argument types.

What is covariant return type the overriding method can have derived type as the return type instead of the base type?

9 Answers. Covariant return, means that when one overrides a method, the return type of the overriding method is allowed to be a subtype of the overridden method’s return type.

What is pure virtual function in C++ with example?

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.

Why virtual function is used 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.

Can overloaded operators be virtual?

4 Answers. If you want to override a virtual function in a child-class, then you need to declare the function override in the child class. So yes, the declaration is needed.

What is Constexpr in C ++ 11?

The keyword constexpr was introduced in C++11 and improved in C++14. It means constant expression. constexpr indicates that the value, or return value, is constant and, where possible, is computed at compile time.

What are covariant return types in C++?

If the return type of a virtual function is a pointer or a reference to a class, override functions can return a pointer or a reference to a derived class. These are called covariant return types. Here is an example:

How do you know if a function is covariant?

If a function D::f overrides a function B::f, the return types of the functions are covariant if they satisfy the following criteria: the class in the return type of B::f is the same class as the class in the return type of D::f, or is an unambiguous and accessible direct or indirect base class of the class in the return type of D::f

Can a virtual function have a different return type than base class?

There is one special case in which a derived class virtual function override can have a different return type than the base class and still be considered a matching override. If the return type of a virtual function is a pointer or a reference to a class, override functions can return a pointer or a reference to a derived class.

Can a derived class override a virtual function using a return type?

Show activity on this post. In some cases, yes, it is legal for a derived class to override a virtual function using a different return type as long as the return type is covariant with the original return type. For example, consider the following: