1. Introduction of Programming
Lecture 27

2. Today’s Lecture Classes and objects Constructors Destructors
Member functions
Member data

3. Function Oriented

4. Object Oriented

5. Multiple
Media

6. Classes
Objects
Constructors

7. Data Hiding
Encapsulation

8. Constructor

9. Bugs

10. The majority of programming
problems occur because of the
use of un-initialized data.

11. Constructor Name of the constructor is same as the name of the class
It does not return any thing, not
even void

12. Example class Date { int month ; int day ; int year ; public:
Date ( int day = 1 , int month = 1 , int year = 1 )
} ;

13. Function Overloading

14. Rules of function overloading
When ever we overload a function,
the name of the function remain the
same but argument list changes.
The argument list can:
Either vary in the number of
arguments
Or vary in the type

15. Example class Date { public :
Date ( int month = 1 , int day = 1 , int year = 1 ) ;
private :
int month , day , year ;
} ;

16. Example
main ( ) {
Date mydate ( ) ; }

17. Example
main ( ) {
Date mydate ( “01-Jan-2002” ) ; }

18. Memory Allocation Inside a Constructor

19. Utility Functions

20. Friend Functions

21. Destructor

22. ~

23. Rules of Destructor Destructors cannot be overloaded
Destructors take no arguments
They don’t return a value

24. Example 1 public : class Date { Date ( ) ;
Date ( int month , int day , int year ) ;
~Date ( ) ;
setMonth ( int month ) ;
setDay ( int day ) ;
setYear ( int year ) ;
int getDay ( ) ;
int getMonth ( ) ;
int getYear ( ) ;
setDate (int day, int month, int year ) ;
private:
int month , day , year ;
} ;

25. Example 1
main ( ) {
Date mydate ( 35 , 13 , 2000 ) ; }

26. Example 1 main ( ) { Date mydate ; mydate.setDate ( 21 , 01 , 1979 ) ;}

27. Example 1
main ( ) {
Date mydate ( 21 , 01 , 1979 ) ; }

28. What Happens in Memory Functions setMonth ( int month ) ;
setDay ( int day ) ;
setYear ( int year ) ;
int getMonth ( ) ;
int getDay ( ) ;
int getYear ( ) ;
int month ;
int day ;
int year ;
int month ;
int day ;
int year ;
int month ;
int day ;
int year ;

29. Example 2 main ( ) { Date date1 , date2 , date3 ;
date1.setMonth ( 3 ) ;
date2.setDay ( 23 ) ; }

30. Destructors
~className ( ) ;

31. Destructors
~Date :: Date ( ) {
cout<< “Object Destroyed” ; }

32. Constructors Date :: Date ( ) { cout << “Date Object Created” ;}

33. Constructors without Arguments
Date :: Date ( ) {
cout<< “Default constructor without arguments called ” ; }

34. Constructors with Arguments
Date :: Date ( int month , int day , int year ) {
cout<< “A constructor with paramerters ” ; }