Half Term 2

Question 1

Bubble Sort

How does a bubble sort work?

Answer 1

• Compare first set of numbers
• If second number is less than first, swap them
• Compare next set of numbers
• Repeat to end of list
• Start again from the first pair in the list
• Repeat until no pairs need to be swapped

Question 2

Bubble Sort

How many times does a list have to be scanned?

Answer 2

The maximum number of times a list has to be scanned through the length of the list -1

Question 3

Bubble Sort

What is the basic bubble sort algorithm?

Answer 3

repeat [number of items - ] times
for each adjacent pair of items in the list
if first of pair is greater than second of pair
swap

Question 4

Bubble Sort

When should a bubble sort be used?

Answer 4

A bubble sort is good for sorting small lists of data

Question 5

Object Oriented Programming

What is Object Oriented Programming?

Answer 5

A programming paradigm based on the concept of ‘objects’ which contain attributes and methods

Question 6

Object Oriented Programming

What is a class?

Answer 6

A class is like a template to ensure that all objects of a certain category have the same kinds of attributes and methods

Question 7

Object Oriented Programming

What are the components of a class?

Answer 7

Classes are made up of the class name, its attributes and its methods

Question 8

Object Oriented Programming

What are the benefits of OOP?

Answer 8

Once a class is defined, it is very easy to create hundreds of objects using it

Question 9

Object Oriented Programming

What is instantiation?

Answer 9

Instantiation is the process of creating an object from a class template

Question 10

Object Oriented Programming

What is a constructor?

Answer 10

A constructor is a special method which runs when an object is created from the class. It contains “new”. Objects are instantiated by calling the class’ constructor

Question 11

Object Oriented Programming

What is the syntax for instantiation?

Answer 11

objectName = new ClassName(“attribute1”, “attribute2”)

Question 12

Object Oriented Programming

What is encapsulation?

Answer 12

All of the object’s attributes are contained and hidden in the object by giving them the private access modifier. They are accessed through public getter and setter methods

Question 13

Object Oriented Programming

What is the benefit of encapsulation?

Answer 13

Data cannot be changed accidently so reducing the chance of errors, ensures changes to attributes are only made in the way that is intended

Question 14

Object Oriented Programming

What is an object/instance?

Answer 14

Objects or instances are the things created using a class’ template

Question 15

Object Oriented Programming

How do you define class functions/methods?

Answer 15

When defining class functions, the keyword “this” must be used to declare class variables (not “let” or “var”) e.g.
constructor() {
this.x = 200;
this.y = 150;

Question 16

Object Oriented Programming

What is the pseudocode for passing arguments into class constructors

Answer 16

constructor (x,y) {
this.x = x;
this.y = y;
}

object = new class(100,200)

Question 17

Object Oriented Programming

What is inheritance?

Answer 17

A mechanism that allows an instance of a class to inherit attributes and methods from another class (the superclass/parent class). It can also have methods/attributes of its own

Question 18

Object Oriented Programming

What is polymorphism?

Answer 18

The ability of an entity such as a variable, operator, method or object to have more than one form

Question 19

Object Oriented Programming

What is overriding?

Answer 19

When an inherited method is superseded by a method defined in the subclass (an example of polymorphism)

Question 20

Object Oriented Programming

What is overloading?

Answer 20

When methods have the same name but different signatures. The signature can differ by the number of parameters or type of parameters or both (an example of polymorphism)

Question 21

Object Oriented Programming

What is an access modifier?

Answer 21

For example public and private which can be applied to attributes and methods in the class. Private means the attribute or method can not be accessed by code in another class while public means it can

Question 22

Object Oriented Programming

What is an attribute?

Answer 22

A specific piece of data representing a particular characteristic of an object

Question 23

Object Oriented Programming

What is a method?

Answer 23

For example getters and setters and other subroutines that define the behaviour of the object

Question 24

Logic Gates & Truth Tables

NOT gate symbols and truth table

Answer 24

¬ ~ ! -
0 → 1
1 → 0

Question 25

# Logic Gates & Truth Tables AND gate symbols and truth table

Answer 25

^ * & 0 0 → 0 0 1 → 0 1 0 → 0 1 1 → 1

Question 26

# Logic Gates & Truth Tables OR gate symbols and truth table

Answer 26

v + || 0 0 → 0 1 0 → 1 0 1 → 1 1 1 → 1

Question 27

# Logic Gates & Truth Tables XOR gate symbols and truth table

Answer 27

⊻ ⊕ 0 0 → 0 1 0 → 1 0 1 → 1 1 1 → 0

Question 28

# Logic Gates & Truth Tables How do you create a truth table from a logic diagram?

Answer 28

* Create a column for each input * List combinations * Create columns for interim outputs * Find outputs

Question 29

# Stacks & Queues What is a stack?

Answer 29

A stack is an essential data structure. Items are pushed to the top of the stack when added and popped off the top when deleted. It's possible to peek at the top item without deleting. It's a LIFO structure

Question 30

# Stacks & Queues What is a LIFO structure?

Answer 30

Last In First Out - The last item to be pushed onto the stack must also be the first to be popped off

Question 31

# Stacks & Queues What is a stack pointer?

Answer 31

A stack pointer points to the node at the top

Question 32

# Stacks & Queues What are stack underflow/overflows?

Answer 32

Stack overflow is an attempt to push an item onto a full stack. Underflow is an attempt to pop an item off of an empty stack

Question 33

# Stacks & Queues How are the stacks implemented?

Answer 33

Stacks are often implemented with an array but could use object-oriented techniques instead

Question 34

# Stacks & Queues How are stacks used?

Answer 34

* Stacks are used by processor to track the flow of programs. When a subroutine is called, it changes the value of the program counterto the first instruction of the subroutine. When the subroutine ends, the PC must return to its previous value. Stacks allow subroutine calls to be nested * Local variables are held on stacks - their values are lost when a subroutine ends because they are popped off the stack. Interrupts can also be handled with a stack * Performing depth-first searches on graph structures * Keeping track of user inputs * Undo operations * Backtracking algorithms * Evaluating mathematical expressions without brackets

Question 35

# Stacks & Queues What is a queue?

Answer 35

A queue is a linear data structure. Items are enqueued at the back of the queue and dequeued from the front of the queue. You can peek at the front item. In special situations, new items can join at the front. It's a FIFO structure

Question 36

# Stacks & Queues What is a FIFO structure?

Answer 36

First In First Out - back/tail pointer points to last item, front/head pointer points at first item

Question 37

# Stacks & Queues What is the problem with creating a queue with an array?

Answer 37

In an array, since the back and front