Pseudocode, VB & Python QuickRef

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Description VB.NET Python Pseudocode (Edexcel) Pseudocode (OCR) Pseudocode (Eduqas)

This resource is designed as a quick revision guide for use by students during a NEA providing that internet access is allowed. It has not been endorsed by any exam boards. If you spot any mistakes, please let me know and I'll fix them asap.

Introduction

This website aims to give a quick reference for VB.NET, Python and pseudocode and is aimed primarily at teachers & students working towards a GCSE in Computer Science

VB.NET and Python are both programming languages designed to be understood and followed by computers. Pseudocode is not a programming language: it's written to be understood by humans so that they can turn it into any programming language.

Each exam board has published a document saying how they'll write pseudocode in their exams. The whole idea of syntax (a set of rules) for pseudocode is silly - it's not designed to be a programming language that is run by a computer. With this in mind, all exam boards state that you don't have to follow the syntax for 'their' version of pseudocode when you write out your own algorithms, but you should be able to understand their version of pseudocode when reading an algorithm in an exam.

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Skill

Description

Pseudocode (Edexcel)

VB.NET

Python

Pseudocode (OCR)

Pseudocode (Eduqas)

Create and use a function

A function is like a procedure except that it always returns a value.

This return value is calculated when the function is called and can be saved into a variable or used later in the program.

Both functions and procedures are sections of code that have been given a name, which can be re-used to do something useful.

This example defines a function which chooses a random word. This function is called twice with the return value being stored into separate variables.

# define ChooseRandomWord function FUNCTION ChooseRandomWord() BEGIN FUNCTION SET words TO ["wibble", "wobble", "plop"] INTEGER i SET i TO RANDOM(2) RETURN i END FUNCTION # Call ChooseRandomWord twice STRING FirstWord SET FirstWord TO ChooseRandomWord() STRING SecondWord SET SecondWord TO ChooseRandomWord()

' define ShowRandomWord function Function ShowRandomWord() dim words As String() words = {"wibble", "wobble", "plop"} dim i As Integer i = Rnd() * 2 Return words(i) End Function ' Call ShowRandomWord twice Dim FirstWord As String FirstWord = ShowRandomWord() Dim SecondWord As String SecondWord = ShowRandomWord()

import random # define choose_random_word function def choose_random_word(): words = ["wibble", "wobble", "plop"] return random.choice(words) # call choose_random_words twice first_word = choose_random_word() second_word = choose_random_word()

// this code assumes there is a function defined called random(min, max) // which chooses a random number between a minimum and maximum (inclusive) // this is not in the pseudocode spec // define choose_random_word function function choose_random_word() switch random(1, 3) case 1: return "wibble" case 2: return "wobble" case 3: return "plop" endswitch endfunction // call choose_random_words twice first_word = choose_random_word() second_word = choose_random_word()

{ not specified in eduqas pseudocode reference }

Create and use a function with parameters

A function is like a procedure except that it always returns a value.

Parameters are variables that allow you to send data to the function to customise what it does or how it works.

The parameters are the variables named in brackets after the function name.

This return value is calculated when the function is called and can be saved into a variable or used later in the program.

Both functions and procedures are sections of code that have been given a name, which can be re-used to do something useful.

This example defines a function which will generate and return a random number. It has two parameters which allow you to set the minimum and maximum number the random number will be between.

This function is called to choose a random number between 10 and 20 and then called again to choose a random number between 50 and 100. Both numbers are returned and saved into separate variables.

# Define the function FUNCTION ChooseRandomBetween(min, max) BEGIN FUNCTION INTEGER n SET n TO RANDOM(max - min) + min RETURN n END FUNCTION # Call the function INTEGER FirstNumber SET FirstNumber = ChooseRandomBetween(10, 20) INTEGER SecondNumber SET SecondNumber TO ChooseRandomBetween(50, 100)

' Define the function Sub ShowRandomBetween(min As Integer, max As Integer) dim n As Integer n = (Rnd() * (max - min)) + min Return n End Function ' Call the function Dim FirstNumber As Integer FirstNumber = ShowRandomBetween(10, 20) Dim SecondNumber As Integer SecondNumber = ShowRandomBetween(50, 100)

import random # define the function def choose_random_between(min, max): print(random.randint(min, max)) # call the function first_number = choose_random_between(10, 20) second_number = choose_random_between(50, 100)

// this code assumes there is a function defined called random(min, max) // which chooses a random number between a minimum and maximum (inclusive) // this is not in the pseudocode spec // define the function function choose_random_between(min, max): return random(min, max) endfunction // call the function first_number = choose_random_between(10, 20) second_number = choose_random_between(50, 100)

{ not specified in eduqas pseudocode reference }