3. Disclaimer: This presentation is prepared by trainees of
baabtra as a part of mentoring program. This is not official
document of baabtra –Mentoring Partner
Baabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt . Ltd
4. OOP CONCEPT
• Object-oriented programming (OOP) is a style of
programming that focuses on using objects to design
and build applications.
• Think of an object as a model of the concepts,
processes, or things in the real world that are
meaningful to your application
5. OBJECT
• Which will have a name as identity
• Properties to define its behaviour
• Actions what it can perform
• It has two main properties:
– State: the object encapsulates information about
itself - attributes or fields.
– Behaviour: the object can do some things on
behalf of other objects – methods.
6. OBJECT(contd)
• Example:
In a banking system, a particular bank account is an
example of an object.
– Its state consists of attributes like: owner, account
number, balance, etc.
– Its behaviours consist of: deposit, withdraw, etc.
7. CLASS
• We need to create a base design which defines the
properties and functionalities that the object should
have.
• In programming terms we call this base design as
Class.
• We can create any number of objects from a class.
• Each individual object is called an instance of its
class.
8. CLASS(contd)
• The actions that can be performed by objects become
functions of the class and is referred to as Methods.
• No memory is allocated when a class is created. Memory
is allocated only when an object is created.
• Example:
Banking system is an example for class.
Different accounts are example for objects.
9. How to create class in C++
class shape //create a class
{
public: Int width;
Int height;
Int calculateArea()
{
return x*y
}
}
10. ATTRIBUTES
Contain current state of an object.
• Attributes can be classified as simple or complex.
• Simple attribute can be a primitive type such as
integer, string, etc.
• Complex attribute can contain collections and/or
references.
• Complex object: contains one or more complex
attributes
11. METHODS
• Defines behavior of an object, as a set of
encapsulated functions.
• The class describes those methods.
• It defines what an object can do.
12. INHERITANCE
Inheritance allows child classes inherits the
characteristics of existing parent class.
• Attributes (fields and properties)
• Operations (methods)
Child class can extend the parent class.
• Add new fields and methods
• Redefine methods (modify existing behavior)
13. INHERITANCE-Example/* C++ Program to calculate the area of rectangles using concept of inheritance.
#include <iostream>
using namespace std;
class Rectangle{
protected:float length, breadth;
public:
Rectangle(): length(0.0), breadth(0.0){
cout<<"Enter length: "; cin>>length;
cout<<"Enter breadth: "; cin>>breadth;
}};
/* Area class is derived from base class Rectangle. */
class Area : public Rectangle{
public:
float calc(){
return length*breadth;
}};
int main(){
cout<<"Enter data for rectangle to find area.n";
Area a;
cout<<"Area = "<<a.calc()<<" square meternn";
return 0;
}
14. ABSTRACTION
• Abstraction means ignoring irrelevant features,
properties, or functions and emphasizing the
relevant ones.
• Abstraction = managing complexity.
• Allows us to represent a complex reality in terms of a
simplified model.
• Abstraction highlights the properties of an entity that
we need and hides the others.
15. ENCAPSULATION
• Encapsulation hides the implementation
details
• Class announces some operations (methods)
available for its clients – its public interface
• All data members (fields) of a class should be
hidden-Accessed via properties (read-only and
read-write)
16. Example for Abstraction and Encapsulation
#include <iostream>
using namespace std;
class Adder{
public:// constructor
Adder(int i = 0){
total = i;}
// interface to outside world
void addNum(int number){
total += number;}
// interface to outside world
int getTotal(){
return total;};
private:// hidden data from outside world
int total;};
int main( ){
Adder a;
a.addNum(10); a.addNum(20); a.addNum(30);
cout << "Total " << a.getTotal() <<endl;
return 0;
}
17. POLYMORPHISM
• Polymorphism is the ability to take more than
one form.
• Polymorphism allows abstract operations to
be defined and used.
• Polymorphism allows routines to use variables
of different types at different times.
18. Example for Polymorphism
#include <iostream>
using namespace std;
class Shape { protected:int width, height;
public: Shape( int a=0, int b=0) { width = a; height = b; }
int area() { cout << "Parent class area :" <<endl; return 0; } } ;
class Rectangle: public Shape{
public:Rectangle( int a=0, int b=0):Shape(a, b) { }
int area (){
cout << "Rectangle class area :" <<endl; return (width * height);}};
class Triangle: public Shape{
public:Triangle( int a=0, int b=0):Shape(a, b) { }
int area (){
cout << "Triangle class area :" <<endl; return (width * height / 2);}};
// Main function for the program
int main( ){
Shape *shape; Rectangle rec(10,7); Triangle tri(10,5);
// store the address of Rectangle
shape = &rec;
// call rectangle area.
shape->area();
// store the address of Triangle
shape = &tri;
// call triangle area.
shape->area();
return 0; }
19. FUNCTION OVERLOADING
• It is simply defined as the ability of one
function to perform different tasks.
• For example, doTask() and doTask(object O)
are overloaded methods.
• To call the latter, an object must be passed as
a parameter, whereas the former does not
require a parameter, and is called with an
empty parameter field.
20. Example for Function Overloading
#include <iostream>
// volume of a cube
int volume(int s){
return s*s*s;
}
// volume of a triangle
float volume(int b, int h){
return 0.5*b*h;
}
// volume of a cuboid
long volume(long l, int b, int h){
return l*b*h;
}
int main(){
std::cout << volume(10);
std::cout << volume(9, 7);
std::cout << volume(100, 75, 15);
}
In the above example, the volume of various components are calculated using the same function
call "volume", with arguments differing in their data type or their number.
21. OPERATOR OVERLOADING
• Different operators have different
implementations depending on their
arguments.
• Operator overloading is generally defined by
the language, the programmer, or both.
• We can redefine or overload most of the built-
in operators available in C++.
22. Example for Operator Overloading
#include<iostream>
class complex
{
public: int real,imaginary;
complex operator+(complex ob)
{
complex t;
t.real=real+ob.real;
t.imaginary=imaginary+ob.imaginary;
return(t);
}
};
int main()
{
complex obj1,obj2,result;
obj1.real=12; obj2.imaginary=3;
obj2.real=8; obj2.imaginary=1;
result=obj1+obj2 // result=obj1.operator+(obj2);
cout<<result.real<<result.imaginary;
return 0;
}
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