Destructors are not only used in classes but also used with struct and union data types. When you construct an object, sometimes you need operations to deconstruct. Do you want to learn what is Virtual Destructor or what kind of methods we have that we can declare and use a virtual destructor? In this post, we will try to explain how to use Virtual Destructor in your C++ apps.
What is a C++ Constructor?
The Constructor in C++ is a function, a method in the class, but it is a ‘special method’ that is automatically called when an object of a class is created. We don’t need to call this function. Whenever a new object of a class is created, the Constructor allows the class to initialize member variables or allocate storage. This is why the name Constructor is given to this special method. Here is a simple constructor class example below,
|
1 2 3 4 5 6 7 8 9 10 |
class myclass { public: myclass() { std::cout << "myclass is constructed!\n"; }; }; |
What is a C++ Destructor?
The Destructor in classes (i.e class_name) is a special member function to delete objects, in other terms it is called when the lifetime of an object ends. The purpose of the destructor is to do operations when destruct the object. The object may have acquired or allocated data on memory on runtime, they need to be freed too when objects are being deleted, destructor is the function that frees the resources of the object. When we construct an object, sometimes we need operations to deconstruct. Destructors are not only used in classes but also used with struct and union data types.
|
1 2 3 4 5 6 7 8 9 10 |
class myclass { public: ~myclass() // Destructor { }; }; |
What is a Virtual Destructor in C++?
in C++The Destructor in classes (i.e. class_name) is a special member function to delete objects, in other terms it is called when the lifetime of an objects ends. The purpose of the destructor is to do operations when destruct the object. Object may have acquired or allocated data on memory on runtime, they need to be freed too when objects are being deleted, destructor is the function that free the resources of object.
Virtual Destructor is usually required in a base class, and it is used by the class which has this base class. Note that, deleting a class object through pointer to base invokes undefined behavior unless the destructor in the base class is virtual:
Syntax,
|
1 2 3 |
virtual ~class_name (); |
Virtual destructor declaration example in a class,
|
1 2 3 4 5 6 7 8 9 10 |
class myclass { public: virtual ~myclass() // Virtual Destructor { }; }; |
An example to virtual destructor in C++,
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 |
#include <iostream> class my_baseclass { public: virtual ~my_baseclass() // Virtual Destructor { std:: cout << "class object deleted safely\n"; } }; class my_class : public my_baseclass { }; int _tmain(int argc, _TCHAR* argv[]) { my_baseclass *test = new my_class; delete test; // Deleted safely by the Virtual Destructor getchar(); return 0; } |
Design. Code. Compile. Deploy.
Start Free Trial
Free C++Builder Community Edition
