U2a - Programming Basics

Question 1

Define data type

Answer 1

The kind of values that can be used in a data item.

Question 2

Name 5 data types

Answer 2

Integer, float/real, character, string, boolean

Question 3

Define arithmetic operator

Answer 3

A symbol that will perform an operation on numbers e.g. +, -

Question 4

What do constants look like?

Answer 4

They’re typically shown in uppercase and the words are separated with an underscore, eg. MIN_AGE
This is known as snake case.

Question 5

Why declare a constant instead of a variable?

Answer 5

This prevents the value from being changed accidentally by a part of a code. It shows a programmer that the value should stay the same throughout the program.

Question 6

Can a constant ever change its value?

Answer 6

A constant cannot be changed when the program is running. However, a constant can be changed by a programmer before the program is compiled or translated.

Question 7

What is used to convert data types? (AKA Casting)

Answer 7

Functions

Question 8

Why should you use comments in your programs? (3)

Answer 8

• To describe the purpose of the program
• To state the author of the program
• To explain what the code does

Question 9

Define sequence

Answer 9

Statements are executed one by one in the order they are written

Question 10

Define selection

Answer 10

An IF statement is a selection statement. The next statement to be executed depends on whether the condition being tested is True or False

Question 11

Comparison operators

Answer 11

= equal to
=/ not equal to
> greater than
< less than

Question 12

Define iteration

Answer 12

Iteration means repetition of a section of code

Question 13

Three types of iteration statement

Answer 13

• FOR..ENDFOR
• WHILE…ENDWHILE
• REPEAT…UNTIL

Question 14

When would you use a for loop

Answer 14

When you want to execute the loop a specific number of times

Question 15

When would you use a while loop

Answer 15

When you want to execute the loop while a certain condition is true

Question 16

When would you use a repeat until loop

Answer 16

When you want to execute the loop until a certain condition is true

Question 17

Define an array

Answer 17

A data structure that allows you to hold many items of data which is referenced by one identifier

Question 18

Do all items of data in the array have to be the same data type?

Answer 18

Yes

Question 19

How would you find an array’s length?

Answer 19

LEN(array)

Question 20

How would you add red to an array?

Answer 20

array[index e.g. 0]

Question 21

Which out of lists and arrays have a fixed length?

Answer 21

Arrays

Question 22

How can you add more items to an array?

Answer 22

You would need to create a new larger array and copy the items across

Question 23

How does a linear search work?

Answer 23

Each item is examined in sequence until the item is found or the end of the list is reached.

Question 24

How does a bubble sort work?

Answer 24

• Each item in a list is compared to the one next to it, and if it is greater, they swap places
• At the end of one pass through the list, the largest item is at the end of the list
• This is repeated until the items are sorted

Question 25

What is a record?

Answer 25

A data structure consisting of a number of fields which can all be of different types

Question 26

What is a field (records)?

Answer 26

A field is a single item of data in a record

Question 27

What is instantiation?

Answer 27

New instances of a record structure being made

Question 28

Define algorithm

Answer 28

A set of instructions for solving a problem or completing a task

Question 29

Define abstraction

Answer 29

Removing unnecessary detail from a problem so that you can focus on the essentials

Question 30

Define decomposition

Answer 30

Breaking down a large problem into smaller sub-problems. Then the sub-problems can be broken down further until each small task is manageable.

Question 31

Advantages of decomposition (2)

Answer 31

- The problem becomes easier to solve when it consists of a number of small subtasks or modules - Some modules may be reusable in other programs, saving development time

Question 32

Define variable

Answer 32

A location in memory in which you can temporarily store text or numbers

Question 33

Define real

Answer 33

A number with a decimal point

Question 34

Define string

Answer 34

One or more characters enclosed in quote marks

Question 35

How does a binary search work?

Answer 35

The size of the list is approximately halved each time an item is examined. ROUND DOWN when even number of choices.

Question 36

What is the condition of a binary search?

Answer 36

The list has to be sorted. If it isn't, it isn't possible to do a binary search. A linear search may be carried out instead.

Question 37

How to merge sort

Answer 37

- Divide the unsorted list into n sublists, each containing one element - Repeatedly merge two sublists at a time to produce new sorted sublists until there is only one sublist remaining. This is the sorted list

Question 38

Which is more efficient, merge sort or bubble sort

Answer 38

Merge sort because it's much quicker

Question 39

Disadvantage of bubble sort

Answer 39

It's slow and inefficient for more than a few items - a list of n item takes roughly n^2 comparisons

Question 40

Disadvantage of merge sort

Answer 40

The merge sort requires more memory to store the sublists, and with a very large number of items this can be a disadvantage