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could result in issues if you have intensive or partially-completed code
that results in an infinite loop)
Exited code editor: will automatically execute code when the code editor
loses
focus - i.e. when you click outside of the code editor
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run/play
button
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Pseudocode
Write and run pseudocode
Java
See a Java equivalent to your pseudocode program
Note: the site doesn't allow executing Java. An IDE like IntelliJ will provide an easy installation of the JDK and is recommended for running Java locally
Python
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Note: the site doesn't allow executing Python. An IDE like PyCharm will provide an easy installation of the Python interpreter and is recommended for running Python locally
Visual Basic
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Note: the site doesn't allow executing Visual Basic. An IDE like Visual Studio will provide an easy installation of the Visual Studio compiler and is recommended for running Visual Basic locally
New Program
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Can use the BREAKPOINT keyword to add breakpoints at specific parts of your program
Use TRACE_NEXT_ROW to force new row to be created in trace table
Autoformat Code
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Pretty-printing/auto-formatting code will insert new lines, indentation and apply consistent styling rules. If enabled, pretty-printing will also occur each time you run your program
You can even try writing your entire program on one line...and it should still run and be formatted correctly :)
Note: code may be re-ordered (e.g. all declarations moved to the top) due to the way the site works
Tested and works for all demo programs - please contact me if this breaks any of your working code!
The site aims to enforce the statically-typed nature of pseudocode - i.e. assigning a STRING to
an
INTEGER variable should be forbidden. Some combinations are allowed, however - such as assigning
a
CHAR to a STRING or an INTEGER to a REAL. Other additional checks to ensure valid pseudocode are
also in place
The site has been well-tested and there aren't any bugs we are aware of, however, if you believe
the
site is incorrectly giving you an error & preventing your code from running, you can disable the
error-checking
Note that it is not possible to disable fatal error messages such as syntax errors, runtime
errors
etc
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Keyword/Identifier/Module Name Suggestions
Subroutine parameters & types
Return types
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Examples
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Use Assignment Arrow
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Allow LENGTH() for Arrays
Turning this on will disable the warning message if using the LENGTH function to get the number of elements in an array
Require Variable Initialisation
If enabled, you will get warnings if trying to access uninitialised variables
Code Snippets
These are pre-written code templates - for example, if you type in "DECLARE" in the code editor, you will see options to declare single variables, 1 & 2D arrays - you can disable this option
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Max Execution Time
To prevent infinite loops resulting in the page becoming unresponsive, code will automatically
terminate if this value (in seconds) is exceeded
If you have a legitimate long-running program, you can obviously set this to a high value -
alternatively, setting to -1 will disable this check
{"0":"Algorithms","1":"Selection","2":"Iteration","3":"Arrays","4":"Records","5":"ENUMs","6":"Custom Modules","7":"Files","8":"Object-Oriented Programming","9":"Abstract Data Types","10":"Sets","11":"Pointers","12":"Recursion","13":"Exam Questions","14":"Games","15":"Mathematics","16":"Art","17":"Utilities","18":"Other"}
Welcome to Pseudocode Pro
This site was developed to solve the problems of students either being completely stuck with pseudocode,
or attempting a solution, but having no way of actually validating if it would work (other than a manual
trace table). This site supports the entire Cambridge IGCSE (0478), O-Level (2210) and 9618 A-Level pseudocode
specifications from the guide/syllabus, with extension modules supporting sound, canvas, events, custom html etc
Below are lists of both the currently support pseudocode and general website features:
Additional coding challenges (I will create 2 per day, will have 500 in total eventually)
Starter code & implementation of pre-defined modules for IGCSE/O-Level/A-Level past papers, so
students can write and test their solutions directly, as they would in the exam
Those last 2 features are currently in progress, so an extra 3 months free
will be given to anyone who buys a license now to acknowledge this
For any issues, feature requests, comments etc, you can contact me
Token List
Work in progress: some buttons currently don't work...just select "All"
Token
Description
Example
Parameters
Thanks for using the site - I hope you enjoy it and if you do, it would mean a lot if you could share it with your friends too :)
Trace Table ✥
New Row
Module Call
Will start a new line when entering a new module - e.g.
PROCEDURE a()
//new line in trace table
...
ENDPROCEDURE
After Parameters
Will start a new line after parameters have had their values traced
PROCEDURE a(b : INTEGER)
//b's value is traced
//new line in trace table
...
ENDPROCEDURE
Loop Iteration
Will start a new line upon each iteration of a loop
REPEAT
//new line in trace table
...
UNTIL index = 10
Pre Loop
Will start a new line before a loop has started
//new line in trace table
REPEAT
...
UNTIL index = 10
Post Loop
Will start a new line after a loop has ended
REPEAT
...
UNTIL index = 10
//new line in trace table
If Statement
Will start a new line inside an IF or ELSE condition
IF a > b THEN
//new line in trace table
ELSE index = 10
//new line in trace table
ENDIF
Left to Right
Many suggest that trace tables should be read left-to-right, top to bottom. Hence, if a value on the current row is to be updated, but a value in a column further right on the same row has already been updated, a new row should be started
If we have the column order a, b and the following assignments...
b <-- 1
a <-- 2
b <-- 3
Then the following trace table should be created (note how the assignment to 'a' has to start a new line, since we have already assigned to a variable in a column to the right ('b')
a
b
1
2
3
Extra Options
Show Duplicates
Usually, the same value being assigned to a variable that it already contains won't be shown on a trace table - by default, it's shown by cells with a black/grey striped background. Enable this option if you'd like the value to be shown instead
a <-- 111
a <-- 111
Show Line Numbers
Show the line numbers in the cell where the value was updated - rather than having to hover your mouse over that cell
Trace All
Trace all variables, even if its order not explicitly specified in the box to the left
Hover or click to show help
Trace table only generated when this dialog is open
Specify variables & order to trace above - default is all, in order they are declared
Hovering your mouse over a cell will display the line number this value was assigned
Use BREAKPOINT keyword to pause execution at specific point
Use TRACE_NEXT_ROW to force creation of a new row at specific point
Grey/black diagonally-shaded cells indicate the value assigned is unchanged
Work in progress. Currently buggy for records, classes, sets etc - will be fixed soon :)
Re-run program for changes to take effect
Program Tokens ✥
Note: tokens were generated via a series of regex rules
Type
Value
Line
Char
Abstract Syntax Tree ✥
Flowchart ✥
Loading... :)
{"c":"\/\/ * Code Author: aesaibnahmed@gmail.com\n\/\/ * Date: 2026\/02\/07\n\/\/ * Description: \n\/\/ * Categories: \n\n\/\/ * Code Author: aesaibnahmed@gmail.com\r\n\/\/ * Date: 2026\/02\/07\r\n\/\/ * Description: \r\n\/\/ * Categories: \r\n\r\n\/\/ * Code Author: aesaibnahmed@gmail.com\r\n\/\/ * Date: 2026\/02\/06\r\n\/\/ * Description: \r\n\/\/ * Categories: \r\n\r\n\/\/ * Code Author: aesaibnahmed@gmail.com\r\n\/\/ * Date: 2026\/02\/06\r\n\/\/ * Description: \r\n\/\/ * Categories: \r\n\r\n\/\/ * Code Author: aesaibnahmed@gmail.com\r\n\/\/ * Date: 2026\/02\/06\r\n\/\/ * Description: \r\n\/\/ * Categories: \r\n\r\n\/\/ Challenge 1: Hello World\r\n\/\/ Create a program to ask for a user's name, then output a greeting to them\r\n\/\/ Examples:\r\n\/\/ If they input their name as Fred , then the program should output Hello Fred! \r\n\/\/ Extension:\r\n\/\/ Add code to keep asking the user to try again, if they don't enter a valid name (e.g. no characters). You could add additional validation rules yourself if you'd like - for example, perhaps the name has to only contain characters in the set A-Z\r\n\r\n\r\n\/\/ Defining functions.\r\n\r\n\/\/ This function will take the user's name.\r\nFUNCTION TakeUserName RETURNS ARRAY OF STRING\r\n \/\/ This will contain all the user's input concatenated.\r\n DECLARE UserInput:ARRAY[1:2] OF STRING\r\n \/\/ This variable will be used to store the name.\r\n DECLARE UserName:STRING\r\n \/\/ This will store a character depending on the type of loop the user wants the program to use.\r\n DECLARE DesiredImplementation:CHAR\r\n \/\/ The user is prompted to enter their desired implementation of the program.\r\n OUTPUT \"Would you like the program to use a WHILE (w) or FOR (f) loop?: \"\r\n INPUT DesiredImplementation\r\n \/\/ The user is prompted to input their name.\r\n OUTPUT \"The character limit is 10.\"\r\n OUTPUT \"Please enter your name, or type -1 or q to exit: \" \r\n INPUT UserName \/\/ Their input is stored in the variable.\r\n\r\n UserInput[1] \u2190 UserName\r\n UserInput[2] \u2190 DesiredImplementation\r\n\r\n RETURN UserInput\r\n\r\n \r\nENDFUNCTION\r\n\r\n\/\/ This function will check whether the input is valid.\r\nFUNCTION CheckNameValidityFOR(UserName:STRING) RETURNS INTEGER\r\n \/\/ This variable will store a value depending on the nature of the input.\r\n DECLARE Validity:INTEGER\r\n \/\/ This variable will hold the set of acceptable characters.\r\n DECLARE ValidSet:ARRAY[1:26] OF CHAR\r\n \/\/ The letters A-Z are acceptable.\r\n ValidSet \u2190 ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']\r\n \/\/ Selection based on the input.\r\n \/\/ This returns -1 if the user wishes to terminate the program.\r\n IF UserName = \"-1\" OR LCASE(UserName) = \"q\" THEN\r\n RETURN -1\r\n ELSE\r\n IF UserName = \"\" THEN\r\n Validity \u2190 0 \/\/ If nothing was input, 0 is returned.\r\n ELSE\r\n IF LENGTH(UserName) > 10 THEN\r\n Validity \u2190 2 \/\/ If the input was too long, 2 is returned.\r\n ELSE\r\n \/\/ This variable will store the number of acceptable characters in the user's input.\r\n DECLARE CharsAccepted:INTEGER\r\n CharsAccepted \u2190 0 \/\/ Initialize to 0.\r\n \/\/ This stores each character temporarily for comparison with the valid character set.\r\n DECLARE NameChar:CHAR\r\n \/\/ Iterates through each character in the user's input.\r\n FOR Chars \u2190 1 TO LENGTH(UserName)\r\n \/\/ Each time, the current character is stored temporarily for comparison.\r\n NameChar \u2190 LCASE(SUBSTRING(UserName, Chars, 1))\r\n \/\/ Iterates through the valid character set.\r\n FOR ValidChar \u2190 1 TO 26\r\n \/\/ Checks if the current character being checked from the user's input matches the current character being checked against in the valid set.\r\n IF ValidSet[ValidChar] = NameChar THEN\r\n \/\/ If yes, the counter for accepted characters is incremented.\r\n CharsAccepted \u2190 CharsAccepted + 1\r\n ENDIF\r\n NEXT ValidChar\r\n NEXT Chars\r\n \/\/ Checks if the number of accepted characters is equal to the number of characters inputted, i.e. if all the inputted characters were accepted\r\n IF CharsAccepted = LENGTH(UserName) THEN\r\n Validity \u2190 1 \/\/ If yes, 1 is returned.\r\n ELSE\r\n Validity \u2190 3 \/\/ If the input contained unacceptable characters, 3 is returned.\r\n ENDIF\r\n ENDIF\r\n ENDIF\r\n ENDIF\r\n \/\/ The status of acceptability of the input is returned.\r\n RETURN Validity\r\nENDFUNCTION\r\n\r\n\/\/ This function will check whether the input is valid.\r\nFUNCTION CheckNameValidityWHILE(UserName:STRING) RETURNS INTEGER\r\n \/\/ This variable will store a value depending on the nature of the input.\r\n DECLARE Validity:INTEGER\r\n \/\/ This BOOLEAN will specifically store a value depending on if the user's input contained invalid characters.\r\n DECLARE ValidityString:BOOLEAN\r\n ValidityString <- TRUE\r\n \/\/ This variable will hold the set of acceptable characters.\r\n DECLARE ValidSet:ARRAY[1:26] OF CHAR\r\n \/\/ The letters A-Z are acceptable.\r\n ValidSet \u2190 ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']\r\n \/\/ Stores the current character from the user's input being checked for.\r\n DECLARE CurrentChar:CHAR\r\n \/\/ Counter that stores the current index of the valid set being checked against.\r\n DECLARE SetCount:INTEGER\r\n \/\/ Boolean for whether the current character being checked for was found in the valid set, i.e. if the current character being checked for is valid.\r\n DECLARE CharFound:BOOLEAN\r\n \/\/ Counter that stores the current index of the character from the user's input being checked for.\r\n DECLARE CharCount:INTEGER\r\n CharCount \u2190 1\r\n \/\/ Selection based on the input.\r\n \/\/ This returns -1 if the user wishes to terminate the program.\r\n IF UserName = \"-1\" OR LCASE(UserName) = \"q\" THEN\r\n RETURN -1\r\n ELSE\r\n IF UserName = \"\" THEN\r\n Validity \u2190 0 \/\/ If nothing was input, 0 is returned.\r\n ELSE\r\n IF LENGTH(UserName) > 10 THEN\r\n Validity \u2190 2 \/\/ If the input was too long, 2 is returned.\r\n ELSE\r\n WHILE ValidityString = TRUE AND CharCount <= LENGTH(UserName) DO\r\n CurrentChar \u2190 SUBSTRING(LCASE(UserName),CharCount,1)\r\n SetCount \u2190 1\r\n CharFound \u2190 FALSE\r\n WHILE CharFound = FALSE AND SetCount <= 26 DO\r\n IF CurrentChar = ValidSet[SetCount] THEN\r\n CharFound \u2190 TRUE\r\n ENDIF\r\n SetCount \u2190 SetCount + 1\r\n ENDWHILE\r\n\r\n IF CharFound = FALSE THEN\r\n ValidityString <- FALSE\r\n ENDIF\r\n\r\n CharCount \u2190 CharCount + 1\r\n\r\n ENDWHILE\r\n\r\n IF ValidityString = TRUE THEN\r\n Validity <- 1\r\n ELSE\r\n Validity <- 3\r\n ENDIF\r\n \/\/ Checks if the number of accepted characters is equal to the number of characters inputted, i.e. if all the inputted characters were accepted\r\n ENDIF\r\n ENDIF\r\n ENDIF\r\n \/\/ The status of acceptability of the input is returned.\r\n RETURN Validity\r\nENDFUNCTION\r\n\r\n\/\/ This function will display a message to the user.\r\nPROCEDURE Reply(UserName:STRING, Validity:INTEGER)\r\n \/\/ Selection based on validity of input.\r\n IF Validity = 1 THEN\r\n \/\/ The user is greeted if the input was valid.\r\n OUTPUT \"Hello \", UserName, '!'\r\n ELSE\r\n IF Validity = 0 THEN\r\n \/\/ If nothing was input, the user is notified accordingly.\r\n OUTPUT \"Nothing was input. Please enter your name.\"\r\n ELSE\r\n IF Validity = 2 THEN\r\n \/\/ If the input was too long, a shorter input is prompted.\r\n OUTPUT \"Exceeded character limit. Enter a nickname or abbreviation instead.\"\r\n ELSE\r\n IF Validity = 3 THEN\r\n OUTPUT \"Acceptable characters are only the 26 letters of the English alphabet.\"\r\n ELSE\r\n \/\/ The user is notified as the program terminates.\r\n OUTPUT \"Terminating.\"\r\n ENDIF\r\n ENDIF\r\n ENDIF\r\n ENDIF\r\nENDPROCEDURE\r\n\r\n\/\/ The main piece of code.\r\nPROCEDURE Main\r\n DECLARE UserInput:ARRAY[1:2] OF STRING\r\n DECLARE Validity:INTEGER\r\n\r\n Validity \u2190 0\r\n\r\n \/\/ The program loop that runs indefinitely until '-1' or 'q' is inputted.\r\n WHILE Validity > -1 DO\r\n \/\/ The values returned by TakeUserName() is stored in a local array.\r\n UserInput \u2190 TakeUserName()\r\n \/\/ Selects based on whether the user wants a WHILE or FOR loop.\r\n IF UserInput[2] = 'w' THEN\r\n OUTPUT \"Using WHILE.\"\r\n \/\/ The input status is checked by the WHILE loop version of CheckNameValidity() and stored.\r\n Validity \u2190 CheckNameValidityWHILE(UserInput[1])\r\n ELSE\r\n OUTPUT \"Using FOR.\"\r\n \/\/ The input status is checked by the FOR loop version of CheckNameValidity() and stored.\r\n Validity \u2190 CheckNameValidityFOR(UserInput[1])\r\n ENDIF\r\n \/\/ The two variables are passed as arguments for the Reply function.\r\n CALL Reply(UserInput[1],Validity)\r\n ENDWHILE\r\nENDPROCEDURE\r\n\r\n\/\/ The main subroutine is called.\r\nCALL Main()","t":"Challenge - Hello World"}
