Virtual Function in C++
A virtual function a member function which is declared within a base class and is re-defined(Overriden) by a derived class. When you refer to a derived class object using a pointer or a reference to the base class, you can call a virtual function for that object and execute the derived class’s version of the function.
Pure Virtual Functions in C++
A pure virtual function (or abstract function) in C++ is a virtual function for which we don’t have an implementation, we only declare it. A pure virtual function is declared by assigning 0 in the declaration.
Similarities between virtual function and pure virtual function
- These are the concepts of Run-time polymorphism.
- Prototype i.e. Declaration of both the functions remains the same throughout the program.
- These functions can’t be global or static.
Difference between virtual function and pure virtual function in C++
|Virtual function||Pure virtual function|
|A virtual function is a member function of base class which can be redefined by derived class.||A pure virtual function is a member function of base class whose only declaration is provided in base class and should be defined in derived class otherwise derived class also becomes abstract.|
|Classes having virtual functions are not abstract.||Base class containing pure virtual function becomes abstract.|
|Definition is given in base class.||No definition is given in base class.|
|Base class having virtual function can be instantiated i.e. its object can be made.||Base class having pure virtual function becomes abstract i.e. it cannot be instantiated.|
|If derived class do not redefine virtual function of base class, then it does not affect compilation.||If derived class do not redefine virtual function of base class, then no compilation error but derived class also becomes abstract just like the base class.|
|All derived class may or may not redefine virtual function of base class.||All derived class must redefine pure virtual function of base class otherwise derived class also becomes abstract just like base class.|
Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.
- What happens when a virtual function is called inside a non-virtual function in C++
- Pure virtual destructor in C++
- Pure Virtual Functions and Abstract Classes in C++
- Virtual Function in C++
- Default arguments and virtual function
- C++ interview questions on virtual function and abstract class
- Difference between Virtual Machines and Containers
- Difference between Chatbot and Virtual Assistant
- Difference Between Virtual Private Network (VPN) and Proxy
- Difference between Parallel Virtual Machine (PVM) and Message Passing Interface (MPI)
- Difference between Virtual Private Network (VPN) and Multi-Protocol Label Switching (MPLS)
- Difference between Virtual memory and Cache memory
- Virtual Destructor
- C++ | Virtual Functions | Question 4
- Virtual base class in C++
- Virtual destruction using shared_ptr in C++
- C++ | Virtual Functions | Question 9
- C++ | Virtual Functions | Question 14
- C++ | Virtual Functions | Question 7
- C++ | Virtual Functions | Question 6
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to email@example.com. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
Improved By : sudeea