✅1.2.5 Object Oriented Programming

Question 1

What is a class?

Answer 1

A template for objects.

Question 2

What is an object?

Answer 2

An instance of a class.

Question 3

What is an attribute?

Answer 3

A value held by an object.

Question 4

What is a method?

Answer 4

An action an object performs.

Question 5

Describe one difference between get and set methods

Answer 5

A get method allows the attribute to be accessed. Whereas a set method allows the attribute to be changed (with parameters).

Question 6

Describe what is meant by the term inheritance [3]

Answer 6

When a class takes on the methods (1) and attributes (1) of a parent class (1).

Question 7

State the term that describes setSalary( ), setQualification( ) or setExtraFee( )

Answer 7

Method

Question 8

Explain the meaning of the arrows in a class diagram

Answer 8

Shows inheritance

Question 9

State the purpose of a constructor

Answer 9

Creates an instance of an object from a class

Question 10

Explain 2 difference between passing a parameter by value and by reference

Answer 10

1. By Value sends the actual value whereas by Reference sends a pointer to the value.
2. With by value, if changes are made then only the local copy is amended. Whereas by reference If changed the original is also changed when the subroutine ends.

Question 11

6iii. State 2 advantages of using encapsulation.

Answer 11

1. Reduces the chance of errors/inconsistences
2. Ensures objects can only be changed in the way intended

Question 12

What is encapsulation?

Answer 12

The practice of grouping attributes and methods within a class.

Question 13

Explain 1 similarity and difference between a record and a class

Answer 13

Similarities:
1. Both store data of different types. Which can be accessed by their names

Differences:
1. A record is a data structure whereas a class is a template for making data structures (objects)

Question 14

Barney would like his linked list to be part of a base program that is saved in a library. This means that it can be reused and changed by other programs. Discuss the benefits of using different object-oriented techniques that Barney could use to achieve this. [12]

Answer 14

1. Classes, this a template. It will define what attributes and methods an object should have.
2. A class can be used to declare the attributes and methods for the linked list. These will initialise the nodes and join them.
3. Objects, when you create an instance of a class. Each object that is instantiated from the same class will share the same attributes and methods.
4. Objects can then be used be used to instantiate the class each time a new linked list is needed. Each can be given a different identifier by the other programs.
5. Encapsulation, this protects attributes of an object by making them private so that they can’t be accessed or altered accidentally by other objects.
6. Encapsulation can be used by using set and get methods to ensure that the nodes in the linked list are changed in a way that is intended.
7. Use of OPP techniques will allow for code reusability. His linked list can be saved as library and then reused many times leading to less code.
8. OOP also allows programs to be easier to modify and maintain.

Question 15

A program is amended to include the use of several queue data structures. Describe how an array can be used to implement a queue data structure. [3]

Answer 15

1. Queue has head pointer and tail pointer. [1]
2. When an item is enqueued the tail pointer increments. [1]
3. When an item is dequeued the head pointer increments. [1]

Question 16

DO OOP PSUEDOCODE QUESTIONS

Answer 16

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