IT1050 Object Orientation Lecture 05

Questions and Answers

What is the purpose of the private section in a class definition?

To define default values for the class members

To provide a summary of the class methods

To allow access to members from anywhere in the program

To restrict access to members from outside the class (correct)

Which of the following correctly describes how methods defined in a class can be accessed?

They are accessible only through the public interface of the class (correct)

They are accessible exclusively from within other class methods

They can only be accessed directly from the class without instantiation

They can be accessed by any part of the program without restrictions

In the Rectangle class implementation, what is the return type of the `calcArea` method?

int (correct)

double

float

void

What is the correct way to set the width of a Rectangle object in C++?

object.setWidth(5); Signup and view all the answers

How should `setLength` modify the length attribute in the Rectangle class?

It should modify the member variable using the passed parameter Signup and view all the answers

What happens if you attempt to access a private member directly from outside the class?

It causes a compile-time error Signup and view all the answers

If you want to calculate the area of a rectangle, which method must be called after setting the dimensions?

calcArea() Signup and view all the answers

What is the expected output if `width` is set to 10 and `length` is set to 5 in the Rectangle class?

50 Signup and view all the answers

What is the purpose of the setStudentNo function in the Student class?

To set the student number Signup and view all the answers

What is the correct implementation of the assignMarks function based on the provided information?

void Student::assignMarks(int n1, int n2, int n3) { marks1 = n1; marks2 = n2; marks3 = n3; } Signup and view all the answers

What is the return type of the calcAvg function in the Student class?

float Signup and view all the answers

In the main function, how is the width of rec1 set using the provided code?

rec1.setWidth(10); Signup and view all the answers

What is the meaning of the following line in the given code: 'float average = (marks1+marks2+marks3)/3.0;'?

This line calculates the average of three mark variables. Signup and view all the answers

How are objects of a class created according to the information provided?

Using the class name followed by the object name; Signup and view all the answers

Which of the following statements regarding access specifiers in the Student class is correct?

Public methods can be accessed from outside the class. Signup and view all the answers

Which of the following is a valid way to create multiple objects of the Rectangle class?

Rectangle rec1; Rectangle rec2; Signup and view all the answers

What is the primary purpose of the private section in a class definition?

To define properties (data members) that are accessible only within the class Signup and view all the answers

Which of the following methods is NOT typically included in a class definition for managing attributes?

initAttributes() Signup and view all the answers

Which term best describes the foundational steps of Object-Oriented Programming (OOP) mentioned?

Problem analysis followed by class and object creation Signup and view all the answers

How are private and public members defined in a C++ class?

Private members cannot be accessed outside the class, whereas public can be Signup and view all the answers

In the context of the Rectangle class example, which of these data types is suitable for the attributes width and length?

int Signup and view all the answers

Which statement accurately reflects OO analysis and design?

It encompasses conceptualizing and designing classes before implementation Signup and view all the answers

What would be a valid implementation to calculate the area of a rectangle in the provided class?

int calcArea() { return length * width; } Signup and view all the answers

Which step comes after identifying the objects in the Object-Oriented Programming process?

Developing classes Signup and view all the answers

Study Notes

Learning Outcomes

Students will learn to implement a class and create objects using C++.

Object-Oriented Programming Steps

Analyze problems and identify objects as part of object-oriented (OO) analysis.
Develop classes and create objects in OO programming.
Build the solution by encapsulating functionality.

Example: Rectangle Class

Class representation of a rectangle includes private data members: width and length.
Public methods defined for the Rectangle class:
- setWidth()
- setLength()
- calcArea() for calculating the area.

Rectangle Class in C++

C++ class structure:
- Private section holds data members (int width, int length).
- Public section defines methods to manipulate the rectangle's properties.

Access Control: Private & Public

Private properties are hidden and cannot be accessed outside the class directly.
Public methods act as interfaces to access and modify private data members.

Implementing Methods

Example implementation in C++:
- setWidth(int no) method assigns a value to the width.
- setLength(int no) method assigns a value to the length.
- calcArea() computes and returns the area of the rectangle.

Student Class Example

Class representation for a student includes:
- Private data members: studentNo, marks1, marks2, marks3.
- Public methods:
  - setStudentNo()
  - assignMarks()
  - calcAvg() for calculating the average of the marks.

Student Class in C++

Structure of the Student class in C++ mirrors the Rectangle class layout for consistency.

Creating Objects

Syntax for creating objects: Class_name Object_name;
- Declare a single object: Rectangle rect1;
- Declare multiple objects: Rectangle rect1, rect2;
- Declare an array of objects: Rectangle rectangles;

Accessing Public Methods

Include libraries and use main() to create and manipulate objects.
Example of setting properties and accessing public methods using standard output (cout).

Summary

Understanding of encapsulation, object manipulation, and class implementation in C++ is fundamental in object-oriented programming.

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Description

This quiz covers the key concepts of classes and objects in C++ as part of the IT1050 Object Oriented Concepts course. Students will learn to implement a class and create objects using the principles of object-oriented programming. Enhance your understanding of C++ and deepen your programming skills with this focused assessment.