Can a destructor be pure virtual 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. You may be wondering why a pure virtual function requires a function body. The reason is because destructors (unlike other functions) are not actually ‘overridden’, rather they are always called in the reverse order of the class derivation. This means that a derived class’ destructor will be invoked first, then base class destructor will be called. If the definition of the pure virtual destructor is not provided, then what function body will be called during object destruction? Therefore the compiler and linker enforce the existence of a function body for pure virtual destructors.
Consider the following program:
The linker will produce following error in the above program.
test.cpp:(.text$_ZN7DerivedD1Ev[__ZN7DerivedD1Ev]+0x4c): undefined reference to `Base::~Base()'
Now if the definition for the pure virtual destructor is provided, then the program compiles & runs fine.
~Derived() is executed Pure virtual destructor is called
It is important to note that a class becomes abstract class when it contains a pure virtual destructor. For example, try to compile the following program.
The above program fails in compilation & shows following error messages.
[Error] cannot declare variable ‘p’ to be of abstract type ‘Test’
[Note] because the following virtual functions are pure within ‘Test’:
[Note] virtual Test::~Test()
[Error] cannot allocate an object of abstract type ‘Test’
[Note] since type ‘Test’ has pure virtual functions
This article was contributed by Meet Pravasi. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
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.
- Virtual Destructor
- Calling virtual methods in constructor/destructor in C++
- Pure Virtual Functions and Abstract Classes in C++
- Difference between Virtual function and Pure virtual function in C++
- Private Destructor
- Difference Between Constructor and Destructor in C++
- Order of Constructor/ Destructor Call in C++
- Is it possible to call constructor and destructor explicitly?
- Pure Functions
- What happens when a virtual function is called inside a non-virtual function in C++
- __attribute__((constructor)) and __attribute__((destructor)) syntaxes in C
- Virtual Function in C++
- Virtual base class in C++
- Can virtual functions be private in C++?
- C++ | Virtual Functions | Question 7
- Virtual destruction using shared_ptr in C++
- Can static functions be virtual in C++?
- C++ | Virtual Functions | Question 6
- C++ | Virtual Functions | Question 5
- C++ | Virtual Functions | Question 4
Improved By : abrahammurciano