Object Oriented Programming is a programming model which is based upon the concept of objects.
| Content |
|---|
| Procedural Programming |
| Object Oriented Programming |
| Class |
| Object |
| Encapsulation |
| Polymorphism |
| Inheritance |
| Abstraction |
| Constructor-Destructor |
Procedural Programming can be defined as a programing Model which is derived from structured Programming Ex:- C
Object Oriented Programming can be defined as a programming model which is based upon the concept of objects. Ex:- C++
| Procedural | Object Oriented |
|---|---|
| Follows Top-Down approach. | Follows Bottom-Up approach. |
| Program is Divided into small parts called functions. | Program is Divided into small parts called objects . |
| No access specifier. | Has access specifier.(Public,Private,Protected). |
| Less Secure. | More Secure. |
| Overloading is not possible. | Overloading is possible . |
| No data hiding and Inheritance. | Data hiding and Inheritance is used. |
| Function is more Important than Data | Data is More Important than Function. |
| Examples: C , Pascal | Examples: C++ , Java , Python |
- Class
- Objects
- Encapsulation
- Polymorphism
- Inheritance
- Abstraction
Class is a user defined datatype which holds data and function.
- Data inside the class is called member data and function are called member functions.
The Binding of Data and the functions together into a single class type variable is called variable encapsulation, which one of the benefites of Object oriented Programming
syntax:
class classname
{
access_specifier_1: MemberData1,MemberFunction1
access_specifier_2: MemberData2,MemberFunction2
access_ specifier_3: MemberData3,MemberFunction3
};access_specifier tells the visiblity or scope Type of Access Specifier
- Public : It's member are accessible everywhere
- Private : It's member are only accessible inside the class
- Protected : It's member are only accessible inside the class and the class that is derived from that class
syntax for defining the Function outside the class:
returntype classname::functionName(){
cout<<"HEllo";
}It is an instence of a class that is varible of a class
syntax To declare Object:
ClassName ObjName;
To access the elements we can use dot operator (Membership Operator)
In Object Oriented Programming , Encapsulation is the concept of Wrapping of data and information in a single unit.
A formale defination of encapsulation would be :
Encapsulation is binding togather the data and related function that can manipulate data.
example:
class Encapsulation{
int data1, data2;
public:
void func1(){
cout<<"This a Function";
}
}
Here,
data1, data2, func1 is encapsulated inside the class Encapsulation
The name defines Itself , Poly = "Multiple" morphism = "Forms" => Multiple Forms
Which means Polymorphism is the ability of object oriented programming to do some work using multiple forms.
example:
class Polymorphism{
public:
void add(int a,int b){
return a+b;
}
void add(int a,int b,int c){
return a+b+c;
}
}
Here,
Add function can add 2 numbers (if we pass 2 variables)
or it can add 3 numbers (if we pass 3 variables)Inheritance is a way to reuse code. It is a way to create a new class from an existing class. The new class is called a subclass (or derived class, or child class). The one it inherits from is called a superclass (or base class, or parent class). The Subclass inherits all the methods and variables from the superclass. It can also add its own methods and variables.
Syntax:
class <derived_class_name>:<Access-Specifier> <base_class_name>{
// Data
}- Public Mode : All the Public data of base class is saved in Public of Derived class, Private data of the base class is saved in Protected of the Derived Class.
- Private Mode : All the Public,Protected data of base class is saved in private of Derived class.
- Protected Mode : All the Public,Protected data of base class is saved in protected of Derived class.
Example:
class Base{
public:
int data1; // Data Member
void function1(int a){
cout<<"The variable Is : "<<a;
}
}
class Derived:Public Base{
}
int main(){
Base B1;
B1.function1(3);
}
// Output: The variable Is :3Abstraction means Displaying only essential Information and hiding the details . Data abstraction refers to providing only essential information about the data and hiding the background details or implementation.
example:
Man Driving a Car : Here he only knows that by pressing the accelerator will increase the speed and breaks will stop the car but he does not know how.
example:
class implementAbstraction {
private:
int a, b;
public:
void set(int x, int y)
{
a = x;
b = y;
}
void display()
{
cout << "a = " << a << endl;
cout << "b = " << b << endl;
}
};
int main()
{
implementAbstraction obj;
obj.set(10, 20);
obj.display();
return 0;
}
Here we are not allowed to access the variable a and b directly,
however,
set() function call access it and modify the values of A and B.- Mobile applications (particularly Android based) : Mobile applications are developed using OOPs concepts. The Android SDK is written in Java and the Android operating system is based on the Linux kernel. The Android SDK provides a set of tools and APIs that allow developers to write applications using the Java programming language.
- Games : Games are developed using OOPs concepts. The game engine is written in C++ and the game is developed using C++. The game engine provides a set of tools and APIs that allow developers to write games using the C++ programming language.
- Graphical User Interface Design GUI is developed using OOPs concepts. The GUI toolkit is written in C++ and the GUI is developed using C++. The GUI toolkit provides a set of tools and APIs that allow developers to write GUI using the C++ programming language.
- Web Applications Web applications are developed using OOPs concepts. The web application framework is written in Java and the web application is developed using Java. The web application framework provides a set of tools and APIs that allow developers to write web applications using the Java programming language.
- Troubleshooting is easier with the OOP language : The OOP language is easier to troubleshoot because it is more organized and structured.
- Code Reusability : Reusability is one of the most important benefits of OOP. It allows you to reuse the code and save time and effort.
- Productivity : Productivity is another important benefit of OOP. It allows you to develop the application faster and more efficiently.
- Data Redundancy : Data redundancy is another important benefit of OOP. It allows you to avoid data redundancy and save time and effort.
- Code Flexibility : Code flexibility is another important benefit of OOP. It allows you to change the code easily and quickly.
- Solving problems : OOP allows you to solve the problems easily and quickly.
- Security : OOP allows you to develop the application more securely.
It is used to access Global variable when there is a Local variable with the same name.
and also used to define or access the function and data outside the class.It is also used to access the static variable and function.
It is denoted by :: (double colon) operator.
syntax:
ClassName::functionName();Access Specifiers are used to define the scope of the data and function within the class.
There are 3 types of Access Specifiers in C++.
- Public
class AccessSpecifier{ public: int data1; void function1(){ cout<<"This is a function"; } } We can access the data and function anywhere in the program. with the help of dot operator (.) .
- Private
class AccessSpecifier{ private: int data1; void function1(){ cout<<"This is a function"; } } We can access the data and function only inside the class.
- Protected
class AccessSpecifier{ protected: int data1; void function1(){ cout<<"This is a function"; } } We can access the data and function only inside the class and the class that is derived from that class.
class Array{
private:
int arr[5];
public:
void getdata(){
for(int i=0;i<5;i++){
cin>>arr[i];
}
}
void display(){
for(int i=0;i<5;i++){
cout<<arr[i]<<" ";
}
}
}
Here,
arr is an array of size 5.
class Array{
private:
int data;
public:
void getdata(){
cin>>data;
}
void display(){
cout<<data;
}
}
int main(){
Array A[5];
for(int i=0;i<5;i++){
A[i].getdata();
}
for(int i=0;i<5;i++){
A[i].display();
}
}class Memory{
private:
int data;
public:
void getdata(){
cin>>data;
}
void display(){
cout<<data;
}
}
int main(){
Memory *ptr = new Memory;
ptr->getdata();
ptr->display();
}We give Special meaning to a particular operator
Operator's that can't be overloaded
1. Conditional (?:)
2. Scope resolution (::)
3. SizeOf (sizeof())
4. Membership (.)
5. Pointer to member (.*)Syntax:
return_type operator operator_symbol(){
// Code
}class Unary{
private:
int data;
public:
void getdata(){
cin>>data;
}
void display(){
cout<<data;
}
void operator--(){
data = --data;
}
}
int main(){
Unary U1;
U1.getdata();
--U1;
U1.display();
}