Unit 1 Fundamentals of Programming

Question 1

What is an algorithm?

Answer 1

A sequence of steps that can be followed to complete a task

Question 2

What is abstraction?

Answer 2

Abstraction involves removing unnecessary detail from a problem so that you can focus on the essentials.

Question 3

What is decomposition?

Answer 3

Breaking a problem down into smaller sub-problems, making the overall problem easier to solve

Question 4

Advantages of decomposition

Answer 4

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

Question 5

Processing

Answer 5

Any operations carried out by a computer system

Question 6

What is a variable?

Answer 6

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

Question 7

Data types

Answer 7

• Integer
• Real
• Boolean
• Character
• String

Question 8

Integer

Answer 8

A whole number

Question 9

Real

Answer 9

A number with a decimal point

Question 10

Boolean

Answer 10

Can only be TRUE or FALSE

Question 11

String

Answer 11

One or more characters enclosed in quote marks

Question 12

Sequence

Answer 12

The statements are executed in the order they are written

Question 13

Selection

Answer 13

• 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 14

Iteration

Answer 14

• Iteration means repetition
• A set of statements are repeated a fixed number of times, or until a condition is met

Question 15

Three types of iteration statements

Answer 15

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

Question 16

FOR…ENDFOR loop

Answer 16

Used when you want to execute the loop a specific number of times

Question 17

WHILE…ENDWHILE

Answer 17

• Used when you want to execute the loop while a certain condition is true
• The condition is tested at the beginning of the loop

Question 18

REPEAT…UNTIL

Answer 18

• Used when you want to execute the loop until a certain condition is true
• The condition is tested at the the end of the loop, it is always executed at least once
• So an IF statement is needed as well as the Repeat loop

Question 19

Describe the process of a binary search

Answer 19

• Examine the middle item of the list first and determine whether the correct data item has been found
• If not, check whether it is before or after the current item in the data set
• Discard the half of the data set that does not contain the item
• Repeat the algorithm until the data item is found or it is not in the data set
• Only works if the data items are in sequence

Question 20

Describe the process of a linear search

Answer 20

• If the list to be searched is not sorted, it is not possible to do a binary search. A linear search may be carried out instead
• Examine each item in turn until the item is found or the end of the data structure/file is reached

Question 21

Comparison of searches

Answer 21

• Linear search the list can be ordered or unordered, but for a binary search the list must be ordered
• A binary search is much more efficient than a linear search because with every iteration of the algorithm, the size of the range of items that needs to be searched decreases by half

Question 22

Explain the process of bubble sorting

Answer 22

• 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 all the items are sorted

Question 23

Explain the process of a merge sorting algorithm

Answer 23

• 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 24

Comparing merge sort to bubble sort

Answer 24

• The merge sort requires more memory to store the sublists, and with a very large number of items this can be a disadvantage
• Merge sort is much more efficient than the bubble sort, the bubble sort is slow and inefficient for more than a few items