Aim: To study and implement Classes and Objects

Software Requried;

Visual Studio

Theory:

In Object Oriented Programming, classes and objects are basic concepts of that are used to represent real-world concepts and entities.

• A class is a template to create objects having similar properties and behavior, or in other words, we can say that a class is a blueprint for objects. An object is an instance of a class.

• A class is a user-defined data type, which holds its own data members and member functions that can be accessed and used by creating an instance of that class. A C++ class is like a blueprint for an object. Data Members: These are the variables that are defined inside the class. Member Functions: Functions declared inside a class. Also referred to as a member method.

When a class is defined, only the specification (attributes and behaviour) for the object is defined. No memory is allocated to the class definition. To use the data and access functions defined in the class, we need to create its objects. Objects are the actual entities that are created as an instance of a class. There can be as many objects of a class as desired Local Class: Classes are generally declared in global scope and are accessible to every function or other classes once they are defined. But C++ also provides facility to define a class within a function. It is called local class in C++ and is only accessible in that function.

Access Specifiers: Access specifiers control how the members (attributes and methods) of a class can be accessed. They help protect data and organize code so that only the right parts can be seen or changed.

In C++, there are three access specifiers:

• public - members are accessible from outside the class
• private - members cannot be accessed (or viewed) from outside the class
• protected - members cannot be accessed from outside the class, however, they can be accessed in inherited classes.

Implementaion:

The Concept of Classes and Objects is demonstrated using the following codes,

• Displaying Student Information using classes
• Displaying Car information using Classes and Methods
• Calculators using Classes
• Calculating the area of rectangle using Classes and Methods
• Calculatiing the volume of a cuboid using Classes and Methods along with usage of private and public members.

Algorithms:

Algorithm: Class and Object in C++ (Student Information)

1. Start
2. Define a class Student with the following public data members: name (string) branch (string) subject (string) year (string) result (float)
3. In the main() function:
   1. Create an object s1 of type Student.
   2. Assign values to s1’s attributes: name = "Yash Rastogi" branch = "ENTC" subject = "C++" year = "2nd Year" result = 9.5
   3. Display all details of s1.
   4. Reassign new values to s1: name = "Yashpratapsingh" branch = "ENTC" subject = "C++" year = "2nd Year" result = 6.9
   5. Display updated details of s1.
4. End

Algorithm: Calculator using Class and Objects

1. Start
2. Define a class Calculator with the following public data members: a, b (float, operands) add, diff, mul, div (float, results) Member functions: input() → to read values of a and b. addition() → compute a + b. subtraction() → compute a - b. mult() → compute a * b. div1() → compute a / b.
3. Define function Calculator::input() to take input of two numbers from user.
4. Define function Calculator::mult() to calculate multiplication.
5. Define function Calculator::div1() to calculate division.
6. In main():
   1. Create an object c1 of class Calculator.
   2. Call c1.input() to read numbers.
   3. Call all calculation functions (mult(), div1(), addition(), subtraction()).
   4. Display results: Addition Subtraction Multiplication Division
7. End

Algorithm: Car Information using Class and Objects

1. Start
2. Define a class Car with the following public data members: car_model (string) car_yr (string) car_brand (string) Member function info() to input car details.
3. Define function Car::info():
   1. Display *"Enter the brand of the Car:" and read car_brand.
   2. Display "Enter the year of manufacture of the Car:" and read car_yr.
   3. Display *"Enter the model of the Car:" and read car_model.
4. In main():
   1. Create an object c1 of class Car.
   2. Call c1.info() to input car details.
   3. Display the stored details: Brand Year of manufacture Model
5. End

Algorithm: Calculate Rectangle Area using Class and Objects

1. Start
2. Define a class rec_area with the following public data members: length (float) breadth (float) area (float) Member function area1() to calculate area.
3. Define function rec_area::area1():
   1. Display "Enter the length of the rectangle:" and read length.
   2. Display "Enter the breadth:" and read breadth.
   3. Calculate area = length * breadth.
4. In main():
   1. Create an object r1 of class rec_area.
   2. Call r1.area1() to input dimensions and calculate area.
   3. Display "Area of the rectangle is:" followed by area.
5. End

Algorithm: Calculate Volume of a Cuboid using Class and Objects

1. Start

2. Define a class cuboid with: Private data members:

   height = 10.0 width = 20.0 length = 45.0 Public member function:

   volume() → calculates and returns height * width * length.

3. In main():

   1. Create an object c1 of class cuboid.
   2. Call the volume() function using object c1 and store the result in variable vol.
   3. Display "Volume:" followed by vol.

4. End

Conclusion:

The Above codes demonstrates the usage of classes and objects in C++ , Then the types of access specifier was also demonstrated using the codes.