#include<iostream.h>
#include<conio.h>
class test
{
private:
int a;
public:
test() // constructor (member initialize)
{
cout<<"\n constructor fired";
}
~test() // Destructor ( ~ tiled) realese memory
{
cout ("\n Destructor fired";
}
};
main()
{
clrscr();
test t1;
getch();
}
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In object-oriented programming, a destructor (sometimes shortened to dtor) is a method which is automatically invoked when the object is destroyed. Its main purpose is to clean up and to free the resources(which includes closing database connections, releasing network resources, relinquishing resource locks, etc.) which were acquired by the object along its life cycle and unlink it from other objects or resources invalidating any references in the process. The use of destructors is key to the concept of Resource Acquisition Is Initialization (RAII).
In binary programs compiled with the GNU C Compiler, special table sections called .dtors are made for destructors. This table contains an array of addresses to the relevant functions that are called when the main() function exits.[1] A function can be declared as a destructor function by definining the destructor attribute __attribute__ ((destructor)) for a static function
In a language with an automatic garbage collection mechanism, it would be difficult to deterministically ensure the invocation of a destructor, and hence these languages are generally considered unsuitable for RAII. In such languages, unlinking an object from existing resources must be done by an explicit call of an appropriate function (usually called Dispose()). This method is also recommended for freeing resources rather than using finalizers for that.
Destructor syntax
C++ has the naming convention in which destructors have the same name as the class of which they are associated with, but prefixed with a tilde (~).
In Object Pascal, destructors have the keyword "destructor" and can have user-defined names (but are mostly called "Destroy").
In Perl, the destructor method is named DESTROY.
In Moose object system for Perl, the destructor method is named DEMOLISH.
In Objective-C, the destructor method is named "dealloc".
In PHP 5, the destructor method is named "__destruct". There were no destructors in previous versions of PHP.
In C++
The destructor has the same name as the class, but with a tilde (~) in front of it. If the object was created as an automatic variable, its destructor is automatically called when it goes out of scope. If the object was created with a new expression, then its destructor is called when the delete operator is applied to a pointer to the object. Usually that operation occurs within another destructor, typically the destructor of a smart pointer object.
In inheritance hierarchies, the declaration of a virtual destructor in the base class ensures that the destructors of derived classes are invoked properly when an object is deleted through a pointer-to-base-class. Objects that may be deleted in this way need to inherit a virtual destructor.
A destructor should never throw an exception.
The destructor has the same name as the class, but with a tilde (~) in front of it. If the object was created as an automatic variable, its destructor is automatically called when it goes out of scope. If the object was created with a new expression, then its destructor is called when the delete operator is applied to a pointer to the object. Usually that operation occurs within another destructor, typically the destructor of a smart pointer object.
In inheritance hierarchies, the declaration of a virtual destructor in the base class ensures that the destructors of derived classes are invoked properly when an object is deleted through a pointer-to-base-class. Objects that may be deleted in this way need to inherit a virtual destructor.
A destructor should never throw an exception.
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