object oriented programming

2. Structure Definitions
struct time
{
int hour;
int min;
int second;
}
Accessing members of structure
time t;
cout<<t.hour;
time * timeptr;
Using pointers
timeptr = &t;
cout<<timeptr->hour;
(*timeptr).hour;
Example

3. Classes and Objects
 A class can be described as a collection of data
members and member functions.
 Functions are called member functions and define a
set of operations that can be performed on the data
members of the class.
 The association of data and member functions are
called encapsulation.

5. Class objects
 The process of creating objects(variables) of the class
is called class instantiation. Necessary resources are
allocated only when the class is instantiated.
 The syntax is as follows:
 Class className ObjectName…..
 Ex: class student s1;

6. Accessing Class members
 Class members are accessed using member access
operator , dot(.)
 Syntax : ObjectName.Datamember;
 Example: Student s1;
 s1.rollno;
 s1.printdetails();

7. Defining member functions
 Member functions of the class can be defined in any
one of the following ways
 Inside the class specification
 Outside the class specification

8. Member functions outside the
class body
Example

9. Access specifiers
 Private: The private members of a class have strict access
control. Only the member functions of the same class can access
these members. It prevents accidental modifications of the data
members.
class person
{
private:
int age;
int getage();
};
Person p1;
p1.age = 10; // cannot access private data
p1.getage(); // cannot access private function

10. Public members
 The members of a class which are visible outside the class
are declared in public section.
class person
{
public:
int age;
int getage();
};
Person p1;
p1.age = 10; // can access public datat
p1.getage(); // can access public function

11. Protected members
 The access control of protected members is similar to
private members and has significance to inheritance.
 Empty classes;
 Class xyz{};
 Class Empty {};

12. Constructors and Destructors
 Constructors:
 The constructor gets called automatically for each
object that has just got created.
 It appears as member function of each class, whether
defined or not.
 It has same name as the class. It may or may not take
parameters .
 It does not return anything
 The prototype is
 Class name(parameter list);
 Example

13. Parameterized constructors
 Constructors with arguments are called parameterized
constructors.
Example

14. Dynamic memory
Operators new and new[]
The new operator offers dynamic storage allocation similar to
the standard library function malloc.
Throws an exception when memory allocation fails.
pointer = new type
pointer = new type [number_of_elements]
int * b;
b = new int [5];
Operators delete and delete[]
delete pointer;
delete [] pointer;
 Example

15. Destructor
 When an object is no longer needed it can be
destroyed. A class can have a member function called
destructor which is invoked when an object is
destroyed.
Example

16. Constructors with default
arguments.

17.  Constructors with dynamic operations
 Example 2

18. Copy constructor

19.  The copy constructor is a special type of parameterized
constructor.
 It copies one object to another.
 It can be called when an object is created and equated
to an existing object at the same time.
 Vector v1(5), v2(5);
 v1= v2; // operator = invoked
 vector v3 = v2; // copy constructor is invoked.
 Vector v3(v2)
 vector *ptr = new vector(v1);

20. Passing Objects as Arguments
 Methods
 Pass by value
 Example
 Pass and return by reference
 Example
 Array of objects

21. this pointer
 The this pointer points at the object with respect to which
the function was called.
 this pointer is always a constant pointer.
 The compiler converts the class into a structure with only
data members.
class dist
{ int feet,inch;
public:
int getfeet();
int getinch();
}
struct dist
{
int feet, inch;
};
int getfeet(dist * const);
int getinch(dist * const);

22. int dist::getfeet()
{
Return feet;
}
int getfeet(dist * const this)
{
return this->feet;
}

23. OPERATOR OVERLOADING
 Operator overloading feature of C++ is one of the
methods of realizing polymorphism.
 Operator overloading helps in
 Extending capability of operators to operate on user
defined data.
 Data conversion
 Operator overloading extends the semantics of an
operator without changing its syntax.

25. Unary operator overloading
 Example with member function
 Example with operator overloading
 Operator keyword
 The keyword operator facilitates overloading of the C++
operators.

26. Operator return values
 idx1 = idx2++;
 Example
 Binary Operator overloading

27. Arithmetic operators
 Adding two objects of a class
 Direct Addition
 Overloaded + operator
 String Example

28. Comparison operators
 Example
 Arithmetic assignment operators

29. Data conversion

30.  Example

31. Conversion between objects of
different classes.
 ClassA objecta;
 ClassB objectb;
 objecta = objectb;
 Conversion routine in the source object’s class is
implemented using an operator function
 In objecta= objectb, objectb is the source object of
classB

32. Conversion between objects of
different classes.
 Example

33. Conversion routine in destination
object: Constructor function
 Example

34. Overloading with friend functions
Example
Example 2

35. Inheritance
 Inheritance is a technique of organizing information
in a hierarchical form.
 Inheritance allows new classes to be built from older
and less specialized class.
 Classes are created by first inheriting all the variables
and behavior defined by some primitive class and then
adding specialized variables and behaviors.
 Inheritance allows code reusability.

37. Base class and derived class

39.  Example

40. TYPES OF INHERITANCE

43. Constructors
Zero argument constructor in base and derived class
Example
Parameterized constructors in base and derived classes
Example
Parameterized constructor in derived class
Example

44. Multilevel Inheritance
 Derivation of a class from another derived class is
called multilevel inheritance.
 Example
 Constructor Example

45. Multiple Inheritance
 Example
 Example

46. Hierarchical Inheritance
Example

47. Multipath Inheritance
 The form of inheritance which derives a new class by
multiple inheritance of base classes, which are derived
earlier form the same base class is known as multipath
inheritance.
 Example

48.  Problems with multipath inheritance:
 Ambiguity due to duplicate copies of members
inherited from the base class.
 Virtual Base class is used to solve the ambiguity issue in
multipath inheritance.

49. Hybrid inheritance

50.  Write a program to implement hybrid inheritance
shown in the diagram. Consider necessary details for
all the classes.