Craig Richardson - Adventures in Python

This edition first published 2015

2015 Craig Richardson

Registered office

John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom

For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com.

The right of the author to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher.

Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books.

Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought.

Trademarks: Wiley and the Wiley logo are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and/or other countries, and may not be used without written permission. Python is a registered trademark of the PSF (Python Software Foundation). Raspberry Pi and the Raspberry Pi Logo are a registered trademark of the Raspberry Pi Foundation, which is a UK registered charity. All other trademarks are the property of their respective owners. John Wiley & Sons, Ltd. is not associated with any product or vendor mentioned in the book.

A catalogue record for this book is available from the British Library.

ISBN 978-1-118-95179-8 (paperback); ISBN 978-1-118-95184-2 (ePub); 978-1-118-95185-9 (ePDF)

To the swans on the river Cam. May you never visit the Fellows of St John's College.

Some of the people who helped bring this book to market include the following:

Editorial and Production

VP Consumer and Technology Publishing Director: Michelle Leete

Associate DirectorBook Content Management: Martin Tribe

Associate Publisher: Jim Minatel

Series Creator: Carrie Anne Philbin

Executive Editor: Craig Smith

Project Editor: Kezia Endsley

Copy Editor: Kezia Endsley

Technical Editor: Alex Bradbury

Editorial Manager: Jodi Jensen

Senior Project Editor: Sara Shlaer

Editorial Assistant: Claire Johnson

Proofreader: Wordsmith Editorial

Marketing

Marketing Manager: Lorna Mein

Marketing Assistant: Polly Thomas

CRAIG RICHARDSON is a freelance software developer and writer based in the UK. When Craig first started using computers in his early teens he had a typing speed of one word a minute and successfully broke several machines. Since then hes studied computer science and software development at school and university and has taught hundreds of people to program with Python. He also now knows how to fix the many computers he breaks.

This book would not have been possible without the support of my friends and family. Cambridge Make Space has been invaluable: the reliability of the old Internet connection really helped me finish the book. Id also like to thank the books editors and members of staff at Wiley for their hard work.

Introduction

ARE YOU AN intrepid adventurer? Do you love trying new things and learning new skills? Would you like to bring your own ideas to life with technology? If the answer is a resounding Yes! then this is the book for you. Your adventures with Python start here! During your adventures youll learn a lot about programming with Python. Youll create some really fun programs along the way, including games and animations.

Before you take your first step, take some time with this introduction to understand what youll be doing and answers some of the questions you might have.

What Is Programming?

First off, what is programming? Put simply, programming is giving the computer a set of instructions to do something you want. For example, when you play a computer game programs determine what the game will do when you press a button and what is displayed on the screen.

Just as programming is giving the computer a set of instructions, a program is a set of instructions that has been written by a programmer.

You write these instructions using a programming language . There are many different programming languages, which you can think of as similar to human languages like English or French. Each programming language has its own way of doing things but they all share the same fundamental concepts.

---

A program is a set of instructions that has been written by a programmer to instruct the computer to do something.

A programming language allows you to give instructions to a computer. With a programming language you can create programs that control what your computer does.

As a programmer, you have a lot of choice when choosing a programming language to use. So why choose Python? Well, Python is a good language to learn for beginners. It is designed so that it is relatively easy for humans to read. The layout and words it uses for its instructions make it easier to learn than other languages, such as Java or C++. Python is even used in the real worldin fact, it is one of the most popular programming languages used by professional programmers, who use it to do all sorts of things, from analysing scientific data to making games. You can see an example of some Python code in .

The code of a program that generates a circular progress bar. You will learn how to create programs like this one in your adventures.

This introduction is intended to help you get set up with Python on your computer. Its here to make sure you start your journey on the right foot and have everything you need to get going.

What Is Python and What Can You Do With It?