Object Orientated Programming

Question 1

What are classes?

Answer 1

• Classes are used as blueprints or templates that can be used to create objects in OOP
• This method allows for reusable and organised code in a modular way

Question 2

What are objects?

Answer 2

• An object is a representation of a real world entity
• A class is a blueprint that describes the properties and behaviours of objects, while an object is a specific instance created using the blueprint

Question 3

What are constructors?

Answer 3

• A special method within a class that is automatically called when an object of that class is instantiated (created)

Question 4

How is a class set up called ItemForSale with 3 attributes: itemName, price, discount

Answer 4

class ItemForSale
private itemName
private price
private discount

Question 5

How to add a new object to a class ItemForSale with 3 attributes

Answer 5

public procedure new (givenItemName, givenPrice, givenDiscount)
itemName = givenItemName
price = givenPrice
discount = givenDiscount
endprocedure

tank = ItemForSale new (“tank”, 20, 5)

Question 6

what is a method and what are the 2 different types?

Answer 6

• A method is a function that is associated with objects or classes that define the behaviour and actions that an object can perform
• The two types are functions and procedures
• Functions: performs a task and returns a value
• Procedure: performs a task but doesn’t return a value

Question 7

Describe a public method

Answer 7

• Accessible and can be invoked by any code within the same class or from any external classes
• Changes to public methods may effect other parts of the code
• Used when you want to provide accessibility of certain functionalities of an object or class to other parts of your program

Question 8

Describe a private method

Answer 8

• Only accessed within the same class and cannot be invoked by external code or other classes
• Changes to private methods have a localised effect
• Used when you have internal implementation details that should not be accessed or used by external code

Question 9

What is an attribute?

Answer 9

• Refers to a data memory or a property associated with an object or class
• They define the state of an object and can have different values for different instances of the same class

Question 10

What is inheritence?

Answer 10

• Allows a class to inherit the properties and behaviours of another class
• Allows a derived class to inherit and utilise existing code from the base class
• The derived class “is a” base class
• E.G: the base class is vehicle and derived class is car. A car “is a” vehicle

Question 11

What is encapsulation?

Answer 11

• The practice of grouping data (attributes) and methods (functions) within a class
• Using encapsulation ensures that data remains secure and is not accidentally modified or misused by controlling access to them using access modifiers (public, private)
• It also helps to organise code by keeping related methods and data together

Question 12

What is abstraction in encapsulation?

Answer 12

• Reduces complexity by hiding the implementation details of the object, making it easier to work with and understand
• Programmers can use methods and classes from other parts of the program without having to understand how they are constructed internally

Question 13

What is polymorphism?

Answer 13

• Allows objects to take on different forms or behaviours
• Different objects can share the same name or behaviour but can work in different ways
• It helps make code more flexible, reusable and easier to manage