This allows the friend function to access private and protected data members of the base class while still allowing derived classes to override it. Virtual functions are not limited to being only members of base classes they can also be declared as friends of a base class.It can be accessed through pointers or references of the base class.įollowing are some rules related to virtual functions. Abstract classes are used to create a common interface for different classes. Virtual functions help to create abstract classes.It allows polymorphism, which means that the same interface can be used for different objects.This enables derived classes to provide their implementation of a function defined in the base class.Derived classes can override virtual functions to change the behaviour of existing objects without having to modify their original source code.This allows you to override the behaviour of a function in a derived class. Virtual functions are resolved at runtime, which means that the compiler does not know which function to call until the program is running.Without virtual functions, it would require extra work for each shape type since the compiler wouldn’t know which version of draw() should be called at compile time so you’d need separate calls like circle->draw(), rectangle->draw(), etc.įollowing are a few features of virtual functions: It can draw multiple shapes (e.g., circles, squares) on screen and treat them uniformly at the same time by invoking their draw() methods via a single call-like shape->draw().It allows late binding, also known as run-time polymorphism.Developers can add or remove features from existing objects, reducing maintenance costs and improving overall flexibility by overriding a virtual function.It provides the ability to create flexible and extensible code.Let’s have a look at the benefits that virtual functions provide: Therefore, the output is “Science Function”.Īlso Read: Inline Function in C++ Advantages of Virtual Function When subjectPtr->display() is called, it triggers the replace display() function of the Science class. A pointer of type Subject* is then designated the address of the Science object. In the main() function, an object of the Science class is created. The Science class is inherited from the Subject class and overrides the display() function. Virtual Function in C++ With Example #include Įxplanation – The above code showcases polymorphism in C++. Let’s have a look at a basic C++ virtual function example. Virtual functions are declared using the “virtual” keyword and they are defined in the header file of the base class. To learn more about what are virtual function programs in C++, you can pursue a full detail-oriented C++ programming course. It allows the programmer to create objects+, a virtual function is a member function with different behaviours but remains within the same type of hierarchy. In C+base class that can be overridden by derived classes.
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