Learn to Program with Small Basic: An Introduction to Programming with Games, Art, Science, and Math

344 Pages·12.204 MB·English

by  Marji M., Price E.

ages 10 and up
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Small Basic is a free, beginner-friendly pro- You’ll also learn to command a turtle nn
gramming language created by Microsoft. to draw shapes, create magical moving text,
Inspired by BASIC, which introduced program- solve math problems quickly, help a knight tt
ming to millions of first-time PC owners in slay a dragon, and more! oo An Introduction to Programming
the 1970s and 1980s, Small Basic is a modern Each chapter ends with creative coding
PP with Games, Art, Science, and Math
language that makes coding simple and fun. challenges so you can take your skills to
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Learn to Program with Small Basic the next level. Learn to Program with Small
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simple activities like displaying messages rr
and drawing colorful pictures, and then work ABOUT THE AUTHOrs aa
your way up to programming games! Learn Majed Marji is a senior development engi- mm
how to: neer at General Motors and an adjunct
faculty member at Wayne State University ww
 Program your computer to greet you
in Michigan. He is also the author of Learn ii
by name tt
to Program with Scratch (No Starch Press).
 Make a game of rock-paper-scissors using hh
Ed Price is a senior program manager in
If/Else statements
engineering at Microsoft. He holds an MBA in SS
 Create an interactive treasure map using technology management and has been a pro- mm
arrays fessor at Bellevue College. He runs customer aa
 Draw intricate geometric patterns with feedback programs for Azure Development, ll
just a few lines of code Visual Studio, and Small Basic. ll

 Simplify complex programs by breaking BB
Covers Small Basic
them into bite-sized subroutines Version 1.x. Windows 7 aa
or higher required. ss
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$34.95 ($40.95 CDN) SMALL BASICSHELVE IN: PROGRAM PriceandMarji
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Learn to Program with
SmaLL BaSic

L e a r n t o
P r o g r a m w i t h
S m aL L B aSi c
an introduction to
Programming with games,
art, Science, and math
by Majed Marji and Ed Price
San Francisco
Learn to Program with SmaLL BaSic. Copyright © 2016 by Majed Marji and Ed Price.
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying, recording, or by any information storage or retrieval
system, without the prior written permission of the copyright owner and the publisher.
20 19 18 17 16 1 2 3 4 5 6 7 8 9
ISBN-10: 1-59327-702-4
ISBN-13: 978-1-59327-702-4
Publisher: William Pollock
Production Editor: Laurel Chun
Cover Illustration: Josh Ellingson
Developmental Editors: Hayley Baker and Tyler Ortman
Technical Reviewer: Vijaye Raji
Copyeditor: Anne Marie Walker
Compositors: Laurel Chun and Kathleen Miller
Proofreader: Lisa Devoto Farrell
Indexer: BIM Indexing & Proofreading Services
For information on distribution, translations, or bulk sales, please contact No Starch Press, Inc. directly:
No Starch Press, Inc.
245 8th Street, San Francisco, CA 94103
phone: [phone]; [e-mail]; www.nostarch.com
Library of Congress Cataloging-in-Publication Data
Names: Marji, Majed, author. | Price, Ed, 1978- author.
Title: Learn to program with small basic : an introduction to programming
with games, art, science, and math / by Majed Marji and Ed Price.
Description: San Francisco : No Starch Press, [2016] | Includes index.
Identifiers: LCCN 2015039128| ISBN 9781593277024 | ISBN 1593277024
Subjects: LCSH: BASIC (Computer program language)
Classification: LCC QA76.73.B3 M3743 2016 | DDC 005.1/3--dc23
LC record available at http://lccn.loc.gov/2015039128
No Starch Press and the No Starch Press logo are registered trademarks of No Starch Press, Inc. Other
product and company names mentioned herein may be the trademarks of their respective owners. Rather
than use a trademark symbol with every occurrence of a trademarked name, we are using the names only
in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the
trademark.
The information in this book is distributed on an “As Is” basis, without warranty. While every precaution
has been taken in the preparation of this work, neither the authors nor No Starch Press, Inc. shall have any
liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or
indirectly by the information contained in it.
Brief c ontentS
Foreword by Vijaye Raji . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxi
Chapter 1: Introducing Small Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 2: Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Chapter 3: Drawing Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Chapter 4: Using Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Chapter 5: Drawing Shapes with Turtle Graphics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
Chapter 6: Getting User Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Chapter 7: Empowering Programs with Math . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Chapter 8: Making Decisions with If Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
Chapter 9: Using Decisions to Make Games . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
Chapter 10: Solving Problems with Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
Chatper 11: Event-Driven Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Chatper 12: Building Graphical User Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165
Chapter 13: Repeating For Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181
Chapter 14: Creating Conditional While Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195
Chapter 15: Grouping Data in One-Dimensional Arrays . . . . . . . . . . . . . . . . . . . . . . . . .207
Chapter 16: Storing Data with Associative Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Chapter 17: Expanding to Higher-Dimension Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Chapter 18: Advanced Text Magic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Chapter 19: Receiving File Input and Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .287
Where to Go from Here . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309

contentS in De tai L
Foreword by Vijaye raji xvii
acknowLedgmentS xix
introduction xxi
Who Should Read This Book? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxii
What’s in This Book? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxii
Online Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
A Note to the Reader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxiv
1
introducing SmaLL BaSic 1
What Is a Computer? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
What Is a Computer Program? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
What Is Small Basic? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
The Vision of Small Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
The Basics of Small Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
The Small Basic Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
The Small Basic Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
The Small Basic Development Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Installing Small Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
The Small Basic IDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Opening and Saving Your Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Sharing Your Work and Importing Games . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Copy and Paste; Undo and Redo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Running Your Program and Graduating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Writing and Running Your First Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Objects and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Naming Your Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Files Generated by Small Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Helping Hands: IntelliSense and Syntax Coloring . . . . . . . . . . . . . . . . . . . . . . 9
Drawing with Small Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Try It Out 1-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Programming Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2
getting Started 13
The Parts of a Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Comments and Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Characters and Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Arguments and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Try It Out 2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Exploring Other Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Case Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Sequential Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Displaying Numbers and Doing Math . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Joining Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Try It Out 2-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Object Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Setting and Changing Property Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Working with Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Try It Out 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Arithmetic Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Try It Out 2-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Programming Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Syntax Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Logic Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Runtime Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Programming Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3
drawing BaSicS 27
The Graphics Coordinate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Drawing Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Drawing Shapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Triangles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Try It Out 3-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Rectangles and Squares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Try It Out 3-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Ellipses and Circles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Pen Size and Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Pen Width and Shape Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Try It Out 3-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Drawing Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Inserting Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Programming Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4
uSing VariaBLeS 43
What’s a Variable? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
The Basics of Using Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Assigning Expressions to Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Passing Variables to Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Changing the Value of a Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Using Spaces for Readability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Try It Out 4-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Rules for Naming Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Say What You Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Find the Right Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
viii Contents in Detail
Stick with Your Style . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Let IntelliSense Work for You . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Avoid Naming Variables After Methods and Objects . . . . . . . . . . . . . . . . . . 49
Try It Out 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Simplifying Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Try It Out 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Using Variables to Solve Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Try It Out 4-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Two Kinds of Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Global Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Try It Out 4-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Programming Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5
drawing ShaPeS with turtLe graPhicS 55
Meet the Turtle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Moving the Turtle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Absolute Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Relative Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Coloring Your Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Controlling Your Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Try It Out 5-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Introducing the For Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Try It Out 5-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Drawing Regular Polygons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
A Star Is Born . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Try It Out 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Creating Polygon Art Using Nested Loops . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Try It Out 5-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Endless Graphics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Try It Out 5-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Programming Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6
getting uSer inPut 73
Talking to the Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Your Number, Please? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Introducing Yourself to Your Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Writing Prompts for Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
A Moment of Silence, Please (Pause) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Working with User Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Converting Fahrenheit to Celsius . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Try It Out 6-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Averaging Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Reading Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Try It Out 6-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Programming Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Contents in Detail ix