Sec 04 Object-Oriented Programming OOP (Class).pdf

Class
Data Structure Sec 04
Prepared by: Abdullah Emam
Fayoum international Technological University, Department of
Information Technology

What is Object-Oriented Programming?
•OOP is a programming paradigm based on objects and classes.
•It provides a way to structure programs using real-world entities.
•Key concepts:
Encapsulation
Inheritance
Polymorphism
Abstraction

What is a Class?
 A class is a blueprint for creating objects.
 It encapsulates data (variables) and functions (methods).
class Car {
public:
string brand;
int speed;
void display() {
cout << "Brand: " << brand << ", Speed: " << speed <<
" km/h" << endl;
}
};

What is an Object?
 An object is an instance of a class.
 Each object has its own values for the class attributes.
Car car1; // Object creation
car1.brand = "Toyota";
car1.speed = 120;
car1.display();

Declaring a Class in C++
A class is defined using the class keyword.
Example:
class Student {
public:
string name;
int age;
};

Access Specifiers
 Public: Accessible from anywhere.
 Private: Accessible only inside the class.
 Protected: Accessible within the class and derived classes.
class Example {
private:
int secret;
public:
int number;
};

Creating Objects
Student s1;
s1.name = "Alice";
s1.age = 20;

Using Member Functions
 Functions inside the class operate on its data.
class Student {
public:
string name;
int age;
void display() {
cout << "Name: " << name << ", Age:
" << age << endl;
}
};

Constructors
 Constructor initializes objects automatically.
class Student {
public:
string name;
int age;
Student() {
name = "Unknown";
age = 0;
}
};

Parameterized Constructor
 Accepts arguments for initialization.
Student(string n, int a) {
name = n;
age = a;
}

Destructor
 Destructor is called when an object is deleted.
~Student() {
cout << "Destructor
called!" << endl;
}

Encapsulation
Encapsulation protects data by making
variables private and using public
methods.
class Person {
private:
int age;
public:
void setAge(int a) { age = a; }
int getAge() { return age; }
};

Getters and Setters
p.setAge(25);
cout << p.getAge();

Inheritance
 One class (child) derives properties from another (parent).
class Animal {
public:
string name;
};
class Dog : public Animal {
public:
void bark() {
cout << "Woof! Woof!" << endl;
}
};

Exercise 1: Creating a Class and Objects
Problem:
Create a class Book with attributes title, author, and
price. Create objects and display their details using a
function.

#include <iostream>
using namespace std;
class Book {
public:
string title;
string author;
float price;
void display() {
cout << "Title: " << title << ", Author: " << author << ", Price: $" <<
price << endl;
}
};
int main() {
Book b1;
b1.title = "C++ Programming";
b1.author = "Bjarne Stroustrup";
b1.price = 49.99;
b1.display();
return 0;
}

Exercise 2: Encapsulation (Private Members with
Getters and Setters)
Problem:
Create a class BankAccount with private attributes
accountNumber and balance. Provide public getters and
setters for modifying balance safely.

#include <iostream>
class BankAccount {
private:
int accountNumber;
double balance;
public:
BankAccount(int accNum, double bal) {
accountNumber = accNum;
balance = bal;
}
void deposit(double amount) {
balance += amount;
}
void withdraw(double amount) {
if (amount <= balance)
balance -= amount;
else
cout << "Insufficient balance!" << endl;
}
double getBalance() {
return balance;}
};
int main() {
BankAccount account(12345, 500.0);
account.deposit(200);
account.withdraw(100);
cout << "Remaining Balance: $" <<
account.getBalance() << endl;
return 0;
}

Exercise 3: Constructor and Parameterized
Constructor
Problem:
Create a Student class with attributes name and
age. Use a parameterized constructor to initialize
values.

#include <iostream>
class Student {
public:
string name;
int age;
Student(string n, int a) { // Parameterized constructor
name = n;
age = a;
}
void display() {
cout << "Name: " << name << ", Age: " << age << endl;
}
};
int main() {
Student s1("Alice", 20);
Student s2("Bob", 22);
s1.display();
s2.display();
return 0;
}

Exercise 4: Encapsulation and Access Specifiers
Problem:
Create a class Car with private attributes brand and
price. Use public methods to set and get these
values.

class Car {
private:
string brand;
double price;
public:
void setDetails(string b, double p) {
brand = b;
price = p;
}
void display() {
cout << "Car Brand: " << brand << ", Price: $" << price <<
endl;
}
};
int main() {
Car car1;
car1.setDetails("Tesla", 75000.0);
car1.display();
return 0;
}

Sec 04 Object-Oriented Programming OOP (Class).pdf

Sec 04 Object-Oriented Programming OOP (Class).pdf

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