Algorithms and pseudocode

Question 1

what is the program development cycle

Answer 1

analysis - abstraction, decomposition, identification
design - decomposition, structure diagrams, flowcharts, pseudocode
coding - writning code
testing - testing code with test data

Question 2

define decomposition

Answer 2

breaking down a complex problem into smaller, manageable parts which are easier to solve

Question 3

what are the steps of decomposition

Answer 3

• identify main problem
• identify the componenet parts of inputs, processes, outputs and storage
• list the main sub-problems, sub-systems or sub-tasks
• break these down into smaller sub-problems and sub-tasks which can be completed

Question 4

what is a structure diagram used for

Answer 4

to show the structure of a problem, its subsections and links to other subsections

Question 5

what is abstraction

Answer 5

simplifing a porblem so it is easier to be deal with

Question 6

what are flowcharts used for

Answer 6

to develop solutions to a problem

Question 7

what is the problem with using flowcharts

Answer 7

they di not usually translate very easily into program code

Question 8

why do programmers use pseudocode

Answer 8

because it is easier for someone to understand - they can focus on the process needed rather than the coding itself

Question 9

what is the assingment operator for pseudocode

Answer 9

an arrow
<-

Question 10

what is this <

Answer 10

less than

Question 11

what is this >

Answer 11

greater than

Question 12

what is this <>

Answer 12

not equal to

Question 13

what are the data types

Answer 13

• integer
• real
• boolean
• char
• string

Question 14

what is an integer

Answer 14

a whole number

Question 15

what is a real

Answer 15

a number with a decimal point

Question 16

what is a boolean

Answer 16

true or false

Question 17

what is a char

Answer 17

a single alphabetic or numeric character

Question 18

what is a string

Answer 18

a sequence of one or more characters

Question 19

what is the difference between a variable and constant

Answer 19

a variable can be changed/updated/edited after exercution but a constant stores a value that cannot be changed after exercution

Question 20

what are the 3 types of code

Answer 20

• sequence (inputs, outputs, assignment)
• iteration (loops)
• selection (conditions)

Question 21

what is stepqise refinement

Answer 21

when the code happens in order of it being written

Question 22

in pseudocode if statements what do you particually need

Answer 22

IF …
THEN
ELSE IF
THEN
ELSE
END IF

Question 23

what are the three iteration statements

Answer 23

• for … next
• while … endwhile
• repeat … until

Question 24

when are case statements used

Answer 24

if there are several possible options ot be tested

Question 25

how are case statements written

Answer 25

CASE OF ….
1 : …
2 : …
OTHERWISE
ENDCASE

Question 26

what is MOD

Answer 26

the remainder of

Question 27

what is DIV

Answer 27

quotient (normal division)

Question 28

what is sequence

Answer 28

two or more statements written and executed one after the other

Question 29

what are the string operations

Answer 29

LENGTH()
LCASE()
UCASE()
SUBSTRING()

Question 30

how do you write a min algorithm from an array list

Answer 30

ages -> [99, 15, 25, 55, 61]
min -> 100
FOR index -> 1 TO 5
IF ages[index] < min
THEN
min -> age[index]
ENDIF
NEXT index
OUTPUT “The lowest age is “, min

Question 31

how do you write a max algorithm from an array list

Answer 31

ages -> [99, 15, 25, 55, 61]
max -> 0
FOR index -> 1 TO 5
IF ages[index] > max
THEN
max -> age[index]
ENDIF
NEXT index
OUTPUT “The highest age is “, max

Question 32

what is the RLE algorithm

Answer 32

RLE uses frequency/data pairs to encode each run length of the same coloured pixle