Contents:

1. Destructor.

2. When Constructors and Destructors are Called.

Destructor

Is a member function in the class, which has the following characteristics:
1. It has the same name as the class preceded with a tilde '~'. For example, the destructor for class Time is declared:
~Time(

)

2. It doesn't return any type.
3. It is called when objects are destroyed to release all allocated resources.
4. There is just one destructor in a class, it can not be overloaded.
When Constructors and Destructors are Called:

They are called dynamically and that depends on the scope of objects.
Global Scope Objects:

The constructor is called dynamically before any other function even the main function, and the destructor is called dynamically at the end of the main function.
Local Scope Objects:

The constructor is called dynamically when the object is defined, and the destructor is called dynamically at the end of the block of statements where the object is defined.
Example:

1. // Definition of class CreateAndDestroy.
   
2. class
   
   CreateAndDestroy
   
3. {
   
4. public
   
   :
   
5. CreateAndDestroy(
   
   int
   
   value)
   
   // constructor
   
6. {
   
7. data =
   
   value;
   
8. cout
   
   <<
   
   "Object "
   
   <<
   
   data <<
   
   " constructor"
   
   ;
   
9. }
   
10. ~CreateAndDestroy(
    
    )
    
    // destructor
    
11. {
    
12. cout
    
    <<
    
    "Object "
    
    <<
    
    data <<
    
    " destructor "
    
    <<
    
    endl;
    
    }
    
13. }
    
14. private
    
    :
    
15. int
    
    data;
    
16. }
    
    ;
    
17. 
    
18. void
    
    create(
    
    void
    
    )
    
    ;
    
    // prototype
    
19. 
    
20. CreateAndDestroy first(
    
    1
    
    )
    
    ;
    
    // global object
    
21. 
    
22. int
    
    main(
    
    )
    
23. {
    
24. cout
    
    <<
    
    " (global created before main)"
    
    <<
    
    endl;
    
25. 
    
26. CreateAndDestroy second(
    
    2
    
    )
    
    ;
    
    // local object
    
27. cout
    
    <<
    
    " (local in main)"
    
    <<
    
    endl;
    
28. 
    
29. create(
    
    )
    
    ;
    
    // call function to create objects
    
30. CreateAndDestroy fourth(
    
    4
    
    )
    
    ;
    
    // local object
    
31. cout
    
    <<
    
    " (local in main)"
    
    <<
    
    endl;
    
32. return
    
    0
    
    ;
    
33. }
    
34. 
    
35. // Function to create objects
    
36. void
    
    create(
    
    void
    
    )
    
37. {
    
38. CreateAndDestroy fifth(
    
    5
    
    )
    
    ;
    
39. cout
    
    <<
    
    " (local in create)"
    
    <<
    
    endl;
    
40. 
    
41. CreateAndDestroy seventh(
    
    7
    
    )
    
    ;
    
42. cout
    
    <<
    
    " (local in create)"
    
    <<
    
    endl;
    
43. }
    

The Output:
Object 1 constructor (global created before main)
Object 2 constructor (local in main)
Object 5 constructor (local in create)
Object 7 constructor (local in create)
Object 7 destructor
Object 5 destructor
Object 4 constructor (local in main)
Object 4 destructor
Object 2 destructor
Object 1 destructor

Note: You can find the full source code of this example in code.zip file.

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