Python programming for the absolute beginner: Michael Dawson

480 Pages·2010·12.571 MB·English

by  Dawson, Michael

Python® Programming
for the Absolute Beginner,
Third Edition
Michael Dawson
Course Technology PTR
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Python® Programming for the © 2010 Course Technology, a part of Cengage Learning.
Absolute Beginner, Third Edition:
ALL RIGHTS RESERVED. No part of this work covered by the copyright
Michael Dawson
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To my parents, who have read everything I’ve ever written.
A
CKNOWLEDGMENTS
W
riting a book is like giving birth—and I have the stretch marks of the brain
to prove it. So I want to thank all the people who helped me bring my little
bundle of joy into this world.
Thanks to Jenny Davidson for pulling double duty as both project editor and
copyeditor. I appreciated your hard word and attention to detail.
Thanks to Robert Hoag for his technical editing skills. (Thanks for your non-
technical suggestions and good humor too.)
I also want to thank Pete Shinners, original author of Pygame, and all the folks
who contributed to LiveWires. Because of all of you, writing multimedia programs
(especially games!) is now within reach of a new Python programmer.
Last, but certainly not least, I want to thank Matt for his audio expertise, Chris for
his musical talents, and Dave for wearing a chef’s hat.
A A
BOUT THE UTHOR
M
ichael Dawson has worked as both a programmer and a computer game
designer and producer. In addition to real-world game industry experi-
ence, Mike earned his bachelor’s degree in Computer Science from the
University of Southern California. Currently, he teaches game programming in
the Game Production Department of the Los Angeles Film School. Mike has also
taught game programming to students through UCLA Extension and The
Digital Media Academy at Stanford. He’s the author of three other books:
Beginning C++ through Game Programming, Guide to Programming with Python, and
C++ Projects: Programming with Text-Based Games. You can visit his website at
www.programgames.com to learn more or to get support for any of his books.
Table of Contents
Chapter 1 Getting Started: The Game Over Program............. 1
Examining the Game Over Program................................................................................. 1
Introducing Python............................................................................................................... 3
Python Is Easy to Use.................................................................................................... 3
Python Is Powerful........................................................................................................ 3
Python Is Object-Oriented........................................................................................... 3
Python Is a “Glue” Language...................................................................................... 4
Python Runs Everywhere............................................................................................. 4
Python Has a Strong Community............................................................................. 4
Python Is Free and Open Source................................................................................ 5
Setting Up Python on Windows......................................................................................... 5
Installing Python on Windows.................................................................................. 5
Setting Up Python on Other Operating Systems........................................................... 6
Introducing IDLE.................................................................................................................... 7
Programming in Interactive Mode........................................................................... 7
Programming in Script Mode.................................................................................. 10
Back to the Game Over Program...................................................................................... 12
Using Comments......................................................................................................... 12
Using Blank Lines........................................................................................................ 13
Printing the String...................................................................................................... 13
Waiting for the User................................................................................................... 14
Summary................................................................................................................................ 14
Chapter 2 Types, Variables, and Simple I/O: The Useless Trivia
Program..................................................................... 15
Introducing the Useless Trivia Program........................................................................ 15
Using Quotes with Strings................................................................................................. 16
Introducing the Game Over 2.0 Program............................................................. 16
Using Quotes Inside Strings..................................................................................... 18
Printing Multiple Values........................................................................................... 19
Specifying a Final String to Print............................................................................ 19
Creating Triple-Quoted Strings................................................................................ 20
vi Python Programming for the Absolute Beginner, Third Edition
Using Escape Sequences with Strings............................................................................. 21
Introducing the Fancy Credits Program............................................................... 21
Moving Forward a Tab Stop...................................................................................... 22
Printing a Backslash................................................................................................... 22
Inserting a Newline.................................................................................................... 23
Inserting a Quote......................................................................................................... 23
Sounding the System Bell......................................................................................... 23
Concatenating and Repeating Strings........................................................................... 24
Introducing the Silly Strings Program.................................................................. 24
Concatenating Strings............................................................................................... 25
Using the Line Continuation Character................................................................ 26
Repeating Strings........................................................................................................ 26
Working with Numbers..................................................................................................... 27
Introducing the Word Problems Program............................................................ 27
Understanding Numeric Types................................................................................ 28
Using Mathematical Operators................................................................................ 29
Understanding Variables................................................................................................... 30
Introducing the Greeter Program........................................................................... 30
Creating Variables....................................................................................................... 31
Using Variables............................................................................................................ 31
Naming Variables........................................................................................................ 32
Getting User Input............................................................................................................... 33
Introducing the Personal Greeter Program......................................................... 33
Using the input() Function........................................................................................ 34
Using String Methods......................................................................................................... 35
Introducing the Quotation Manipulation Program.......................................... 35
Creating New Strings with String Methods......................................................... 36
Using the Right Types......................................................................................................... 38
Introducing the Trust Fund Buddy–Bad Program.............................................. 38
Tracking Down Logical Errors.................................................................................. 40
Converting Values................................................................................................................ 41
Introducing the Trust Fund Buddy–Good Program........................................... 41
Converting Strings to Integers................................................................................. 42
Using Augmented Assignment Operators............................................................ 44
Back to the Useless Trivia Program................................................................................. 44
Creating the Initial Comments............................................................................... 44
Getting the User Input............................................................................................... 45
Printing Lowercase and Uppercase Versions of name....................................... 45
Printing name Five Times......................................................................................... 46
Calculating seconds.................................................................................................... 46
Calculating moon_weight and sun_weight......................................................... 46
Waiting for the User................................................................................................... 46
Summary................................................................................................................................ 47
Contents vii
Chapter 3 Branching, while Loops, and Program Planning:
The Guess My Number Game................................... 49
Introducing the Guess My Number Game.................................................................... 50
Generating Random Numbers......................................................................................... 50
Introducing the Craps Roller Program.................................................................. 50
Importing the random Module............................................................................... 51
Using the randint() Function.................................................................................... 52
Using the randrange() Function.............................................................................. 52
Using the if Statement....................................................................................................... 53
Introducing the Password Program....................................................................... 53
Examining the if Statement..................................................................................... 55
Creating Conditions................................................................................................... 55
Understanding Comparison Operators................................................................. 55
Using Indentation to Create Blocks........................................................................ 56
Building Your Own if Statement............................................................................. 57
Using the else Clause.......................................................................................................... 57
Introducing the Granted or Denied Program...................................................... 57
Examining the else Clause........................................................................................ 59
Using the elif Clause........................................................................................................... 59
Introducing the Mood Computer Program.......................................................... 59
Examining the elif Clause......................................................................................... 62
Creating while Loops.......................................................................................................... 63
Introducing the Three-Year-Old Simulator Program......................................... 63
Examining the while Loop........................................................................................ 64
Initializing the Sentry Variable............................................................................... 65
Checking the Sentry Variable.................................................................................. 65
Updating the Sentry Variable................................................................................... 66
Avoiding Infinite Loops...................................................................................................... 66
Introducing the Losing Battle Program................................................................ 66
Tracing the Program................................................................................................... 68
Creating Conditions That Can Become False....................................................... 69
Treating Values as Conditions.......................................................................................... 69
Introducing the Maitre D’ Program....................................................................... 70
Interpreting Any Value as True or False................................................................ 71
Creating Intentional Infinite Loops................................................................................ 72
Introducing the Finicky Counter Program........................................................... 72
Using the break Statement to Exit a Loop............................................................ 73
Using the continue Statement to Jump Back to the Top of a Loop................ 73
Understanding When to Use break and continue.............................................. 73
Using Compound Conditions........................................................................................... 74
Introducing the Exclusive Network Program...................................................... 74
Understanding the not Logical Operator.............................................................. 77
Understanding the and Logical Operator............................................................. 78
Understanding the or Logical Operator................................................................ 79
viii Python Programming for the Absolute Beginner, Third Edition
Planning Your Programs.................................................................................................... 80
Creating Algorithms with Pseudocode.................................................................. 80
Applying Stepwise Refinement to Your Algorithms.......................................... 81
Returning to the Guess My Number Game................................................................... 81
Planning the Program................................................................................................ 81
Creating the Initial Comment Block...................................................................... 82
Importing the random Module............................................................................... 83
Explaining the Game.................................................................................................. 83
Setting the Initial Values........................................................................................... 83
Creating a Guessing Loop.......................................................................................... 83
Congratulating the Player........................................................................................ 84
Waiting for the Player to Quit................................................................................. 84
Summary................................................................................................................................ 84
Chapter 4 for Loops, Strings, and Tuples: The Word Jumble
Game........................................................................... 87
Introducing the Word Jumble Game.............................................................................. 87
Using for Loops..................................................................................................................... 88
Introducing the Loopy String Program................................................................. 88
Understanding for Loops........................................................................................... 89
Creating a for Loop..................................................................................................... 90
Counting with a for Loop................................................................................................... 90
Introducing the Counter Program......................................................................... 90
Counting Forwards..................................................................................................... 92
Counting by Fives........................................................................................................ 93
Counting Backwards.................................................................................................. 93
Using Sequence Operators and Functions with Strings............................................ 93
Introducing the Message Analyzer Program........................................................ 94
Using the len() Function............................................................................................ 95
Using the in Operator................................................................................................ 95
Indexing Strings................................................................................................................... 95
Introducing the Random Access Program............................................................ 96
Working with Positive Position Numbers............................................................ 97
Working with Negative Position Numbers.......................................................... 98
Accessing a Random String Element..................................................................... 99
Understanding String Immutability............................................................................ 100
Building a New String...................................................................................................... 101
Introducing the No Vowels Program................................................................... 101
Creating Constants................................................................................................... 102
Creating New Strings from Existing Ones.......................................................... 103
Slicing Strings..................................................................................................................... 104
Introducing the Pizza Slicer Program................................................................. 104
Introducing None...................................................................................................... 106
Contents ix
Understanding Slicing............................................................................................. 106
Creating Slices............................................................................................................ 107
Using Slicing Shorthand.......................................................................................... 108
Creating Tuples.......................................................................................................... 108
Introducing the Hero’s Inventory Program....................................................... 109
Creating an Empty Tuple........................................................................................ 110
Treating a Tuple as a Condition............................................................................ 110
Creating a Tuple with Elements............................................................................ 111
Printing a Tuple......................................................................................................... 111
Looping Through a Tuple’s Elements.................................................................. 111
Using Tuples........................................................................................................................ 112
Introducing the Hero’s Inventory 2.0.................................................................. 112
Setting Up the Program........................................................................................... 113
Using the len() Function with Tuples................................................................... 113
Using the in Operator with Tuples....................................................................... 114
Indexing Tuples......................................................................................................... 114
Slicing Tuples............................................................................................................. 114
Understanding Tuple Immutability..................................................................... 115
Concatenating Tuples.............................................................................................. 115
Back to the Word Jumble Game.................................................................................... 116
Setting Up the Program........................................................................................... 116
Planning the Jumble Creation Section................................................................ 117
Creating an Empty Jumble String......................................................................... 117
Setting Up the Loop.................................................................................................. 118
Generating a Random Position in word.............................................................. 118
Creating a New Version of jumble........................................................................ 118
Creating a New Version of word............................................................................ 118
Welcoming the Player.............................................................................................. 118
Getting the Player’s Guess...................................................................................... 119
Congratulating the Player...................................................................................... 119
Ending the Game....................................................................................................... 119
Summary.............................................................................................................................. 119
Chapter 5 Lists and Dictionaries: The Hangman Game........ 121
Introducing the Hangman Game.................................................................................. 121
Using Lists............................................................................................................................ 123
Introducing the Hero’s Inventory 3.0 Program................................................. 123
Creating a List............................................................................................................ 124
Using the len() Function with Lists....................................................................... 125
Using the in Operator with Lists........................................................................... 125
Indexing Lists............................................................................................................. 125
Slicing Lists................................................................................................................. 125
Concatenating Lists.................................................................................................. 126