1.4.2 Data Structures

Question 1

What is an arrary?

Answer 1

A data structure for storing a finite, ordered set of data of the same data type within a single indentifer

Question 2

What are 3 features of arrays

Answer 2

• Static
• Ordered, made up of elements which each have an index (starting from zero)
• Stored contiguously in memory

Question 3

How do you count the numbers of elements in an array?

Answer 3

length = len[array_name]

Question 4

How do you define an array?

Answer 4

array_name = [“firstelement”,”secondelement”,”thirdelement”]

Question 5

How do you update a value in an array?

Answer 5

array_name[2] = “2nditem”

Question 6

How do you output a value from an arrary?

Answer 6

print(arrary_name[2])

Question 7

What is a 2D array?

Answer 7

Can be visualised as a table or spreadsheet. Arrays inside of an array.

Question 8

How do the indexes work in a 2D array?

Answer 8

array_name[row,column]

The row is called first then the column

Question 9

What are 3D arrays?

Answer 9

A 3D array can be visualised like a pile of 2D arrays.
Think of a stack of spreadsheets.

Question 10

How do the indexes work in 3D arrays?

Answer 10

array_name[row, column, depth]

Question 11

What is a tuple?

Answer 11

A data structure for storing an immutable, ordered set of data, which can be different data types within a single identifier.

Question 12

What does immutable mean?

Answer 12

Cannot be modified morethan once

Question 13

What are 4 features of a tuple?

Answer 13

Mixed data types
Fixed size
Ordered
Immutable

Question 14

What is a list?

Answer 14

A data structure that stores a sequence of data values, each with a unique index

Question 15

What are 4 features of lists?

Answer 15

Ordered
No predefined scope - dynamic
Multiple data types
Stored non-contigously

Question 16

Why are lists easy to initalise?

Answer 16

There is no need to define attributes in advance.

Question 17

What is a record?

Answer 17

A data structure that stores data in elements called fields, organised based on attributes

Question 18

What are 3 attributes of records?

Answer 18

Stores multiple values under one identifier
Can hold different data types
Unordered

Question 19

Why are collections of records usually stored in an array?

Answer 19

So they can be accessed using an index

print(array_name[0].sort)

Question 20

Which operation checks if a list is empty?

Answer 20

.isEmpty()

Question 21

Which operation adds a new value to the end of a list?

Answer 21

.append(value)

Question 22

Which operation removes the value the first time it appears in the list?

Answer 22

.remove(value)

Question 23

Which operation searches for a value in the list?

Answer 23

.search(value)

Question 24

Which operation returns the length of the list?

Answer 24

.length()

Question 25

Which operation returns the position of the item in a list?

Answer 25

.index(value)

Question 26

Which operation inserts a value at a given position in a list?

Answer 26

.insert(position,value)

Question 27

Which operation returns and removes the last value in a list?

Answer 27

.pop()

Question 28

Which operation returns and removes the value in the list at the given position?

Answer 28

.pop(position)

Question 29

What is a stack?

Answer 29

Last in first out data structure (LIFO) Uses one pointer to point to the top of the stack

Question 30

Where are stacks used?

Answer 30

Web browser history Undo buttons

Question 31

How do you add a item to a stack?

Answer 31

Push

Question 32

How do you remove the top item from a stack?

Answer 32

Pop

Question 33

How do you return the value at the top of stack without removing it?

Answer 33

Peek

Question 34

What are the 2 possible errors you could get when pushing/popping?

Answer 34

Popping an item from an empty stack will produce an underflow error Pushing an item onto a full stack will produce an overflow error

Question 35

What is a queue?

Answer 35

A first in first-out data structure (FIFO) Uses two pointers, one to store the location of the front of the queue and one to store the location of the back of the queue.

Question 36

Where are queues used?

Answer 36

Printer queues Keyboard buffers

Question 37

How can you add an item to the back of the queue?

Answer 37

Enqueue

Question 38

How can you remove an item from the front of the queue?

Answer 38

Dequeue

Question 39

How can you output the item from the front of the queue without removing it?

Answer 39

Peek

Question 40

What are the 2 possible errors you can get when dequeuing/enqueuing?

Answer 40

Dequeuing an empty queue will produce an underflow error Enqueuing a full queue will produce an overflow error

Question 41

What is a circular queue?

Answer 41

Circular queues use arrays to make the front of the queue attached to the end of the queue