📘 Classes and Objects in C++

---

🎯 Aim

To study and implement classes and objects in C++, understand the difference between inside and outside class definitions, and explore the role of public and private access specifiers in encapsulation.

---

📚 Theory

In C++, classes and objects are the foundation of Object-Oriented Programming (OOP).

• A class is a blueprint that defines data and functions.
• An object is an instance of a class that holds actual values.

🏗️ Class

• Defines data members (variables) and member functions (methods).
• Can use access specifiers:
  • public → Accessible outside the class.
  • private → Accessible only inside the class.
• Helps in encapsulation (data hiding).

🧑‍🤝‍🧑 Object

• An object is created from a class.
• Each object has its own copy of class variables.
• Example: Car c1; creates an object c1 of class Car.

📝 Function Definitions

• Inside the class → Function body is written directly in the class.
• Outside the class → Function declared inside, defined outside using :: (scope resolution).

---

📊 Comparison Table

⚙️ Feature	🏗️ Class	🧑‍🤝‍🧑 Object
Definition	Blueprint/template	Instance of a class
What it contains	Data members + functions	Real values and operations
Memory Allocation	No memory allocated	Memory allocated when object is created
Example	class Student {…};	Student s1;
Purpose	Defines structure	Works with real data

---

🖼️ Visual Representation

📌 Class → Object Relationship

---

📋 Algorithms

🔹 Cube Volume (Outside Class)

1. Start
2. Define class Cube with private members: side, volume.
3. Declare public functions: input(), calculateVolume(), output().
4. Inside input():
   • Prompt user → enter value of side.
5. Inside calculateVolume():
   • Compute volume = side * side * side.
6. Inside output():
   • Print calculated volume.
7. In main():
   • Create object c2.
   • Call input(), calculateVolume(), and output().
8. End

---

🔹 Cuboid Volume (Inside Class)

1. Start
2. Define class Cuboid with members: length, breadth, height, volume.
3. Create input() function to take values for length, breadth, and height.
4. Create Volume() function to calculate:
   • volume = length * breadth * height.
5. Create Output() function to print volume.
6. In main():
   • Create object v1.
   • Call input(), Volume(), and Output().
7. End

---

🔹 Reverse Array (Outside Class)

1. Start
2. Define class ArrayOps with member function reverseArray(arr[], size).
3. In reverseArray():
   • Loop from i = size - 1 down to 0.
   • Print each element arr[i].
4. In main():
   • Declare array arr[] = {10, 20, 30, 40, 50}.
   • Calculate size of array.
   • Create object obj.
   • Call obj.reverseArray(arr, size).
5. End

---

🔹 Simple Calculator

1. Start
2. Define class Calculator with members: num1, num2.
3. Add member functions:
   • add() → print num1 + num2.
   • subtract() → print num1 - num2.
   • multiply() → print num1 * num2.
   • divide() → if num2 != 0, print num1 / num2, else print error message.
4. In main():
   • Create object c.
   • Take input values for num1 and num2.
   • Call all four functions sequentially.
5. End

---

🔹 Student Details

1. Start
2. Define class Student with members: name, branch, subject, year, result.
3. In main():
   • Create objects S1, S2, S3.
   • Assign details to each object.
   • Example: S1.name = "Ayush Yadav".
4. Print required details (e.g., S1.name).
5. End

---

🧠 Conclusion

This experiment demonstrates the importance of Classes and Objects in C++.

• 🏗️ Class → Defines structure and behavior.
• 🧑‍🤝‍🧑 Object → Real entity with data and functionality.
• ✅ Key Insights:
  • Use inside class methods for simplicity.
  • Use outside class methods for better organization.
  • Classes and objects allow encapsulation, reusability, and real-world modeling in programming.