1.4.2 Data Structures

Question 1

What is an array?

Answer 1

An ordered, finite set of elements of a single type.

Question 2

What type of array is a linear array?

Answer 2

A one dimensional array

Question 3

How can you visualise a two dimensional array?

Answer 3

You can visualise it as a spreadsheet/table

Question 4

How can you visualise a three dimensional array?

Answer 4

A three dimensional array can be visualised as a multi-page spreadsheet

Question 5

What is a record also known as?

Answer 5

A row in a file

Question 6

What is a record made up of?

Answer 6

A record is made up of fields.

Question 7

How can you select a field from a record using pseudocode?

Answer 7

recordName.fieldName

Question 8

What is the definition of a list?

Answer 8

A data structure consisting of a number of items, where the items can occur more than once

Question 9

What are the main differences between arrays and lists?

Answer 9

• Lists can store data non-contiguously
  whereas arrays store data in order.
• Lists can store data of more than one
  data type

Question 10

What is a tuple?

Answer 10

An immutable, ordered set of values of any type

Question 11

What is the difference between a tuple and an array?

Answer 11

Tuples are initialised using regular brackets instead of square brackets

Question 12

What is a stack?

Answer 12

A last in first out data structure, where items can only be removed from and added to the top of the list

Question 13

Give an example of where stacks may be used.

Answer 13

• Back button in a web page
• Undo buttons

Question 14

What is a queue?

Answer 14

A first in first out data structure, where items are added to the end of the queue and removed from the front queue.

Question 15

What does the operation isEmpty() do?

Answer 15

Checks to see if the stack is empty

Question 16

What does the operation push(value) do?

Answer 16

Adds a new value to the top of the stack

Question 17

What does the operation peek() do?

Answer 17

Returns the top value of the stack without removing it

Question 18

What does the operation pop() do?

Answer 18

Returns and removes the value at the top of the stack

Question 19

What does the operation size() do?

Answer 19

It returns the size of the stack

Question 20

What does the operation isFull() do?

Answer 20

Checks to see if the stack is full

Question 21

What does the operation enQueue(value) do?

Answer 21

Adds the value to the end of the queue

Question 22

What does the operation deQueue() do?

Answer 22

Removes the items from the end of the queue

Question 23

What does the operation isEmpty() do?

Answer 23

It checks to see if the queue is empty

Question 24

What does the operation isFull() do?

Answer 24

Checks to see the queue is full