PSEUDOCODE
​GCSE PSEUDOCODE

This section aims to provide a quick reference guide for Pseudocode at GCSE level. Please note that the exact structure expected by the awarding body may change.

ASSIGN VARIABLES
variableName ← value
EXAMPLE: userName ← "Bob

INPUT AND OUTPUT
OUTPUT "This will print to the screen"

OUTPUT "Please enter your name"
INPUT userName
OUTPUT "Welcome back " ,userName ​

CONDITIONALS

IF
IF condition
    THEN
        statements
    ELSE
        statements
ENDIF
​
EXAMPLE:
IF variableName = "Bob"
    THEN
        OUTPUT "Welcome back Bob"
    ELSE
       OUTPUT "User not recognised"
ENDIF

CASE OF
CASE OF <identifier>
    <value 1> : <statement>
    <value 2> : <statement>
    OTHERWISE: <statement>
ENDCASE

EXAMPLE:
OUTPUT "Please select 1, 2 or 3"
​INPUT x
CASE OF x
    1 : OUTPUT "You selected 1"
    2: OUTPUT "You selected 2"
    3: OUTPUT "You selected 3"
    OTHERWISE: OUTPUT "Invalid selection was made"
ENDCASE

LOOPS

REPEAT UNTIL LOOPS
REPEAT
    <Statements>
UNTIL <condition>

EXAMPLE:
​REPEAT
    OUTPUT "Please enter your password"
    INPUT Password
UNTIL Password = "Qwerty"

WHILE LOOPS
WHILE <condition> DO
    <statements>
ENDWHILE

​EXAMPLE:
​password ← ​" "
WHILE password  != "Qwerty" DO
    OUTPUT "Please enter your password"
    INPUT password
ENDWHILE

FOR LOOPS

FOR <identifier> ← <value1> TO <value2>
    <statements>
NEXT <identifier>

EXAMPLE:
FOR index  ← 1 TO 10
    OUTPUT "Loop number ", index
​NEXT index

ARRAYS

EXAMPLE OF CREATING AN ARRAY:
DECLARE <identifier> : ARRAY[<1>:<n>] OF <data type>
DECLARE myList : ARRAY [1:10] OF STRING

EXAMPLE OF ASSIGNING A VALUE TO THE ARRAY
myList[1] ← "Bob"

EXAMPLE OF APPENDING A VALUE TO THE ARRAY
APPEND myList ← "Bob"

EXAMPLE OF REMOVING A VALUE FROM THE ARRAY
DELETE myList[1]

FIND THE LENGTH OF AN ARRAY
OUTPUT LEN(myList)

1. What is the purpose of using pseudocode in the programming process?
2. Can you provide an example of a simple pseudocode algorithm for finding the average of two numbers?
3. Explain the difference between an algorithm written in pseudocode and one written in a programming language.
4. How can using pseudocode make the process of writing a program easier?
5. Coding Challenge 1: Write a pseudocode algorithm to find the largest number in an array of integers.
6. Coding Challenge 2: Write a pseudocode algorithm to determine if a given string is a palindrome.

USEFUL RESOURCES

IB Pseudocode Coding Practice - Practice Pseudocode online with challenges and solutions
IB Pseudocode quick reference - Pseudocode guide on github