PSEUDOCODE CONSTRUCT GUIDE
PSEUDOCODE
CONSTRUCT
GUIDE
FOR CIE COMPUTER SCIENCE 0478 / 2210
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PSEUDOCODE CONSTRUCT GUIDE
TABLE OF CONTENTS
Introduction ..................................................................................................................................... 2
What does this guide contains? ..................................................................................................... 2
Pseudocode Constructs ................................................................................................................... 3
Overview of pseudocode constructs.............................................................................................. 3
1. Datatypes ............................................................................................................................... 4
2. Declaration ............................................................................................................................. 5
3. Assignment .............................................................................................................................. 7
4. Input / Output ......................................................................................................................... 9
5. Decision Making .................................................................................................................... 11
IF‐THEN .............................................................................................................................. 11
CASE‐OF ............................................................................................................................. 13
6. Looping .................................................................................................................................14
FOR‐NEXT ...........................................................................................................................14
WHILE ................................................................................................................................. 15
REPEAT‐UNTIL ...................................................................................................................16
Appendix ......................................................................................................................................... 17
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PSEUDOCODE CONSTRUCT GUIDE
INTRODUCTION
WHAT DOES THIS GUIDE CONTAINS?
This guide contains essential material and syntax rules for writing pseudocode. Example resources
at the end of document also explains the common type of questions that appears in CIE. However, it
should be remembered that this is not an extensive guide for learning pseudocode and should only
be used as a helper reference guide.
Also, please remember that there is no set standard of writing pseudocode and each
teacher/institute uses their own rules to develop pseudocode. For example, some teachers might
use the keyword SET or DECLARE for variable declaration, others might not even use it. Both the
approaches are correct as CIE syllabus (year 2016) does not define any particular method of doing
so.
This guide only covers a specific set of commands & methodology as taught by the authors in their
own schools and does not cover all possible alternatives. Students should not get confuse if any
particular teacher does not use the same syntax rules as defined in this guide.
At the end, remember that pseudocode is all about logic building and not syntax writing! However,
these rules will help you writing good code when you move on to formal programming languages in
‘A levels’.
Go ahead and get started!
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PSEUDOCODE CONSTRUCT GUIDE
OVERVIEW OF PSEUDOCODE CONSTRUCTS
Pseudocode
Storage
I/O
Selection
Variable
INPUT
IF‐THEN
Constant
PRINT
CASE‐OF
Repetition
Counter
FOR‐NEXT
Conditional
WHILE‐
END WHILE
REPEAT‐
UNTIL
Array
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PSEUDOCODE CONSTRUCT GUIDE
1.
DATA TYPES
Following the common data types that are used in pseudocode when declaring variables, constants and
arrays. Some data types can be referred with more than one name; alternative names are also listed.
INTEGER
Data type to hold whole numbers i.e. numbers without decimal value. It contains both positive and
negative numbers

Example: 56 , 27 , ‐25

Use: Mainly used for counting, whole number addition/subtraction etc.
FLOAT / REAL
Data type to hold floating point numbers i.e. numbers with decimal value. It contains both positive
and negative decimal numbers

Example: 72.84 , 0.014 , ‐12.85

Use: Mainly used for money, weight, height, temperature etc.
CHAR
Data type to hold a “single” alphanumeric character.

Example: R , K , s

Use: Mainly used for codes like T or F (True/False), M or F(male/female) etc.
TEXT / STRING
Data type to hold alphanumeric characters. It includes all printable characters including alphabets,
numbers, special symbols and punctuation marks.

Example: Google , CIE2016 , R@N#

Use: Mainly used for names, address etc.
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PSEUDOCODE CONSTRUCT GUIDE
2. DECLARATION
Declaration is a way to tell the computer that you are going to use a particular variable so it should
reserve specific memory to it as well as label it with the name that you give in the declaration. It is
required for variables, constants and arrays and is mostly done at the start of pseudocode, however it is
not compulsory and we can declare them anywhere in our pseudocode but beware that declaration
should always be before the use of variable, constant or array.
VARIABLES
SET
variable_name
AS
data_type
Where:
Variable_name is the name of variable. It can be anything but should be meaningful and
signify the purpose. Variable names should start with an alphabet. 4num is not a valid
variable name since it starts with a number.
data_type is the data type of variable. It could be integer, float, char or string.

Example

SET student name AS String

SET height AS Float
CONSTANTS
constant_name  Value
CONST
AS
datatype
Where:
constant_name is the name of constant. It can be anything but should be meaningful and
signify the purpose. Constant names should start with an alphabet. 4num is not a valid
variable name since it starts with a number.
data_type is the data type of variable. It could be integer, float, char or string.
Value is the fixed value assigned to variable which will not be changed afterwards in
pseudocode or flowchart


Example

CONST pi
 3.141 AS Float

CONST color
 “Red” AS String
Beware

Constant’s value is assigned directly in the declaration. Its value can be read but
cannot be changed later on.
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PSEUDOCODE CONSTRUCT GUIDE
ARRAYS
SET
array_name [1:max]
SET
array_name [max]
AS
AS
datatype
datatype
Where:
array_name is the name of array. It can be anything but should be meaningful and signify
the purpose. Array names should start with an alphabet. 4num is not a valid array name since
it starts with a number.
datatype is the data type of array. It could be integer, float, char or string.
max is the size of an array. It is the number of elements in an array.


Example

SET marks [1:10] AS Integer

SET father names [50] AS String
Beware

An array’s index number cannot be a floating point value nor it can be negative
value. It can only be a positive integer value.
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PSEUDOCODE CONSTRUCT GUIDE
3.
ASSIGNMENT
Values can be assigned to variables, constants and arrays at either declaration or afterwards in
pseudocode.  sign is used to assign values. An important rule to remember is that the values are
always assigned to the variable that is on the left hand side, hence the direction of the arrow will
ALWAYS be towards the left hand side.
VARIABLES
variable_name  Value
variable_name  another_variable
Where:
variable_name is the name of variable that has been already declared.
Value is the data to assigned to variable. It should match with the data type of variable.
String / Text values are always enclosed in double quotes ( “ “ ) and Char values are enclosed
in single quotes ( ‘ ‘ ). Integer & float values are directly assigned.
another_variable is some other variable containing a value.


Example

name  “Koko”

gender  ‘F’

height  5.4

age  20
Beware

Always assign values to variables according to its data type. Assigning text data
to a variable that is declared as Integer is wrong and may lose marks in exams.
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PSEUDOCODE CONSTRUCT GUIDE
ARRAYS
array_name [ index ]  value
array_name [ index ]  another_variable
Where:
array_name is the name of array that has been already declared.
Value is the data to be assigned to array. It should match with the data type of array.
String / Text values are always enclosed in double quotes ( “ “ ) and Char values are enclosed
in single quotes ( ‘ ‘ ). Integer & float values are directly assigned.
Index is the particular element/location in an array


Example

Company [3]  “Blitz Computing”

Active [6]  ‘Y’

price [43]  3454.35

floors [5]  5
Beware

Always assign values to array according to its data type. Assigning text data to an
array that is declared as Integer is wrong and may lose marks in exams.
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PSEUDOCODE CONSTRUCT GUIDE
4. INPUT / OUTPUT
Taking user input is done using INPUT keyword and output is printed using PRINT keyword. Input can
only be stored in either variable or array. Output can be displayed from variables, arrays, constants and
fixed values (string literals).
INPUT
INPUT variable_name
INPUT array_name [index]
Where:
variable_name is the name of variable in which to store the input.
array_name is the name of array in which to store the input.
Index is the particular element/location in an array


Example

INPUT name

INPUT class [6]

INPUT name, father_name, age
Important

Multiple inputs can be taken using single INPUT command by separating them
with comma. (see above example; last one)

Beware

Input cannot be taken in constants. Their value is assigned during declaration
and cannot be changed anywhere in pseudocode.

An array cannot be filled directly by using single INPUT command. You have to
use loop to fill array since it is a collection of variables.
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PSEUDOCODE CONSTRUCT GUIDE
OUTPUT
PRINT variable_name
PRINT array_name [index]
PRINT “string_literal”
Where:
variable_name is the name of variable to be printed.
array_name is the name of an array to be printed.
Index is the particular element/location in an array
string_literal is a fixed text value to be printed. For example a message like “The
answer is”.


Example

PRINT name

PRINT class [6]

PRINT “Your name is “

PRINT name, father_name, age
Important

Multiple values can be printed using single OUTPUT command by separating
them with comma. (see above example; last one)

Beware

String literal values should always be in double quotes as they are treated as text

An array cannot be printed directly by using single OUTPUT command. You have
to use loop to print array since it is a collection of variables
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PSEUDOCODE CONSTRUCT GUIDE
5.
DECISION MAKING
Decision making or branching is a way to direct the flow of pseudocode depending upon a particular
condition. We can use these constructs to check for a condition and depending upon the result either
do something or not.
There are 2 constructs for decision making in pseudocode; CASE‐OF and IF‐THEN.
IF‐THEN have 2 variations; one which checks single condition and the other which can check against a
series of conditions. Both have slight differences in their syntax and are explained below.
IF – THEN (Single condition)
IF condition THEN
instructions
END IF
Where:
condition is the condition to evaluate. Its answer will always be in the form of True or
False.
instructions are the pseudocode statements that will only be executed if the condition
evaluates to true. In simple words, these lines of code will only run if the condition’s answer is
True otherwise they will not run and computer will directly jump to line after END IF
statement

Example

IF weight < 20 THEN
PRINT “You are underweight”
END IF

IF chocolate = “Babli”
count  count + 1
END IF
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PSEUDOCODE CONSTRUCT GUIDE
IF – THEN ‐ ELSE (Multiple conditions)
IF condition THEN
Instructions
ELSE IF condition THEN
Instructions
END IF
Where:
condition is the condition to evaluate. Its answer will always be in the form of True or
False.
instructions are the pseudocode statements that will only be executed if the condition
evaluates to true. In simple words, these lines of code will only run if the condition’s answer is
True otherwise they will not run and computer will directly jump to line after END IF
statement

Example

IF weight < 20 THEN
PRINT “You are underweight”
ELSE IF weight < 35 THEN
PRINT “Your weight is normal
END IF

IF chocolate = “Babli”
THEN
count  count + 1
ELSE IF chocolate = “koko” THEN
count2  count + 2
END IF
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PSEUDOCODE CONSTRUCT GUIDE
CASE‐OF does the same thing as IF‐THEN but it is a bit more concise and clearer to read.
CASE‐OF
CASE variable OF
Compare1:
Instructions
Compare2:
Instructions
END CASE
Where:
Variable is the variable which contains the value that you want to check for.
Compare1-2 are the values which you compare with variable (defined with CASE
command). There can be as many compare statements as you need to test. There is no limit.
instructions are the pseudocode statements that will only be executed if the compare
evaluates to true. In simple words, these lines of code will only run if the condition’s answer is
True otherwise they will not run and computer will directly jump to line after END CASE
statement

Example

CASE weight OF
> 20:
PRINT “You are underweight”
< 35:
PRINT “Your weight is normal
END CASE

CASE chocolate OF
“Babli”:
count  count + 1
“koko”:
count2  count + 2
END CASE
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PSEUDOCODE CONSTRUCT GUIDE
6. LOOPING
Looping or repetition is a way to repeat certain pseudocode instructions either a set number of times
(counting based) or depending upon a particular condition (condition based). Hence there are 2
constructs for looping; FOR‐NEXT for counting based looping and WHILE & REPEAT‐UNTIL for
condition based looping.
WHILE loop and REPEAT‐UNTIL loop have slight difference as how they work. It is explained in their
examples below:
FOR‐NEXT
FOR counter_variable  start TO end
Instructions
NEXT variable
Where:
counter_variable is the variable which does the counting in the loop. Its value will
“start” from the number that you define and will go all the way up to “end” value. By default,
the counting is always done in the increments of +1 but you can change its stepping by using
STEP keyword (see second example below). Also counting can be done in reverse as well
(see last example).
instructions are the pseudocode statements that will be repeated

Example

FOR counting  1 to 75
PRINT “This will be printed 75 times”
NEXT counting

FOR counting  1 to 40 STEP 2
PRINT “This will be printed 20 times”
NEXT counting

FOR counting  20 to 1
PRINT “This will be printed 20 times”
NEXT counting
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PSEUDOCODE CONSTRUCT GUIDE


Beware

Counting can only be done using integer numbers. Floating point counting is not
possible in FOR loop nor does it make any sense.
WHILE – END WHILE
WHILE condition
DO
Instructions
END WHILE
Where:
condition is the condition to check. If the result of comparison returns TRUE, only then
the statements inside DO will be executed.
instructions are the pseudocode statements that will only be executed if the
comparison evaluates to true. In simple words, these lines of code will only run if the
condition’s answer is True otherwise they will not run and computer will directly jump to line
after END WHILE statement

Example

WHILE weight > 100
DO
PRINT “You are overweight”
END WHILE

Important

WHILE is a “true‐based” loop. It will only repeat the instructions if the result of
checking condition is TRUE.
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PSEUDOCODE CONSTRUCT GUIDE
REPEAT – UNTIL
REPEAT
Instructions
UNTIL condition
Where:
condition is the condition to check. If the result of comparison returns FALSE, only then
the statements inside REPEAT will be executed.
instructions are the pseudocode statements that will only be executed if the
comparison evaluates to false. In simple words, these lines of code will only run if the
condition’s answer is False otherwise they will not run and computer will directly jump to line
after UNTIL statement

Example

REPEAT
PRINT “You are overweight”
UNTIL weight < 120

Important

REPEAT is a “false‐based” loop. It will only repeat the instructions if the result of
checking condition is FALSE.
DIFFERENCES BETWEEN FOR‐NEXT, WHILE & REPEAT‐UNTIL
FOR‐NEXT

Repeat statements fixed
number of times

No condition checking
WHILE
REPEAT‐UNTIL

Repeats statements when
condition is true

Repeats statements when
condition if false

Checks condition at the
start of loop

Checks condition at the end
of loop
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PSEUDOCODE CONSTRUCT GUIDE
APPENDIX – A
LIST OF ALL PSEUDOCODE KEYWORDS

SET

IF

AS

THEN

CONST

ELSE

REAL

END IF

FLOAT

WHILE

INTEGER

DO

CHAR

END WHILE

STRING

REPEAT

TEXT

UNTIL

INPUT

FOR

READ

TO

OUTPUT

NEXT

PRINT

CALL
 The above words should not be used as variable, constant or array names as they represent
commands which have special functionality.
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PSEUDOCODE CONSTRUCT GUIDE
APPENDIX – B
MATHEMATICAL OPERATORS
Following are the basic arithmetic operators that allow us to perform different types of mathematical
calculations in our flowchart/pseudocode.
OPERATOR
MEANING
+
Addition
‐
Subtraction
*
Multiplication
/
Division
mod
Remainder
←
Assignment operator. Used to assign values to
variables/constant/array.
COMPARISION OPERATORS
Comparison operators allows us to compare different values.
OPERATOR
MEANING
>
Greater than
<
Less than
>=
Greater than or equal to
<=
Less than or equal to
<>
Not equal to
=
Equal to (In sense of comparison)
Two values can be compared using the above operators and the answer would be in the form of
YES/TRUE or NO/FALSE. For example; if we say 5 > 7, then the answer would be NO/FALSE since 5 is
not greater than 7.
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