The C++ compiler creates an implicitly defined destructor. Do you want to learn about the implicitly defined destructor or what kind of methods we have that we can declare and use with the implicitly defined destructor? In this post, we will try to explain Implicitly Defined Destructor in Classes with given examples.
What is a Constructor in C++?
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,
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class myclass { public: myclass() { std::cout << "myclass is constructed!\n"; }; }; |
What is a Destructor 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 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.
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class myclass { public: ~myclass() // Destructor { }; }; |
What is the implicitly defined destructor in C++?
An implicitly defined destructor is a destructor method with a body generated and compiled and it is not deleted. If a destructor declared and it is not deleted, it can be implicitly defined by the compiler when it is used by other classes. This implicitly defined destructor may have an empty body. If this satisfies the requirements of a constexpr_destructor, the generated destructor is constexpr
In this example below, the implicitly defined destructor is called in the main function from the class1 to destroy the class1, as you see it is declared in my_class and can be implicitly used from the my_otherclass,
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#include <iostream> class my_class { public: ~my_class() // Destructor { std::cout << "Class has been destructed\n"; }; }; class my_otherclass { public: my_class test; // This class has Implicitly-Defined Destructor }; int main() { my_otherclass class1; class1.~my_otherclass(); // Calling a Implicitly-Defined Destructor getchar(); return 0; } |
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