ch 1 oops

 

1️⃣ Introduction to Object Oriented Thinking (OOT)

Object Oriented Thinking is a way of solving problems by modeling real-world entities as objects.

Instead of thinking in terms of functions (like procedural programming), we think in terms of:

• Objects

• Classes

• Data

• Behavior

👉 Real world example:
A Car has:

• Data → color, speed, model

• Behavior → start(), stop(), accelerate()

We combine both in one unit → Object

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2️⃣ Introduction to Object Oriented Programming (OOP)

Object Oriented Programming (OOP) is a programming paradigm that organizes software design around objects rather than functions.

In C++, OOP is implemented using:

• Classes

• Objects

• Inheritance

• Polymorphism

• Encapsulation

• Abstraction

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3️⃣ Comparison: Procedural Programming vs Object Oriented Programming

Basis	Procedural Programming	Object Oriented Programming
Focus	Functions	Objects
Approach	Top-down	Bottom-up
Data Security	Less secure	More secure
Code Reusability	Limited	High (Inheritance)
Example Language	C	C++

🔹 Example (Procedural – C Style)

#include <iostream>
using namespace std;

int add(int a, int b) {
    return a + b;
}

int main() {
    cout << add(5, 3);
}

🔹 Example (OOP – C++)

#include <iostream>
using namespace std;

class Calculator {
public:
    int add(int a, int b) {
        return a + b;
    }
};

int main() {
    Calculator obj;
    cout << obj.add(5, 3);
}

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4️⃣ Features of Object Oriented Paradigm

1. Encapsulation

Wrapping data and functions into a single unit (class).

2. Abstraction

Hiding internal details and showing only necessary features.

3. Inheritance

One class acquires properties of another class.

4. Polymorphism

One function behaves differently in different situations.

5. Message Passing

Objects communicate through function calls.

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5️⃣ Merits of OOP

✅ Code Reusability
✅ Data Security
✅ Easy Maintenance
✅ Real-world Modeling
✅ Scalability
✅ Reduced Complexity

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6️⃣ Demerits of OOP

❌ Larger Program Size
❌ Slower Execution (sometimes)
❌ Complex Design
❌ Not suitable for small programs

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7️⃣ Object Model

The Object Model describes how objects interact and are structured.

It consists of:

1. Abstraction

2. Encapsulation

3. Modularity

4. Hierarchy

5. Typing

6. Concurrency

7. Persistence

👉 In simple words:
Object model defines how real-world entities are converted into software objects.

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8️⃣ Elements of OOPS (Important for Exam)

🔹 Class

Blueprint of object.

class Student {
    int roll;
};

🔹 Object

Instance of class.

Student s1;

🔹 Data Members

Variables inside class.

🔹 Member Functions

Functions inside class.

🔹 Constructor

Special function to initialize object.

🔹 Destructor

Special function to destroy object.

🔹 Inheritance

class A {};
class B : public A {};

🔹 Polymorphism

Function Overloading / Function Overriding

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9️⃣ Input/Output Processing in C++

C++ uses iostream library.

Header File:

#include <iostream>
using namespace std;

Input:

int a;
cin >> a;

Output:

cout << a;

Example:

#include <iostream>
using namespace std;

class Student {
public:
    string name;
    int roll;

    void input() {
        cout << "Enter Name: ";
        cin >> name;
        cout << "Enter Roll: ";
        cin >> roll;
    }

    void display() {
        cout << "Name: " << name << endl;
        cout << "Roll: " << roll << endl;
    }
};

int main() {
    Student s1;
    s1.input();
    s1.display();
}