Python for Everyone 3rd Ed

761 Pages·3·12.396 MB·English

by  Horstmann, Cay, Necaise, Rance

Python
for
Everyone

3/e

Cay Horstmann
Rance Necaise

Cay Horstmann
San Jose State University
Rance Necaise
Randolph-Macon College

Python
for
Everyone

3/e
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10 9 8 7 6 5 4 3 2 1
PREFACE

This book is an introduction to computer programming using Python that focuses on
the essentials—and on effective learning. Designed to serve a wide range of student
interests and abilities, it is suitable for a first course in programming for computer
scientists, engineers, and students in other disciplines. No prior programming expe-
rience is required, and only a modest amount of high school algebra is needed. For
pedagogical reasons, the book uses Python 3, which is more regular than Python 2.
PreHseerne ta rfeu tnhed abmooekn’st kaelsy fefiartsutr.e s:
The book takes a traditional route, first stressing control structures, functions,
procedural decomposition, and the built-in data structures. Objects are used when
appropriate in the early chapters. Students start designing and implementing their
Gowunid calanscsees a inn dC hwapotrekre 9d. examples help students succeed.
Beginning programmers often ask “How do I start? Now what do I do?” Of course,
an activity as complex as programming cannot be reduced to cookbook-style
instructions. However, step-by-step guidance is immensely helpful for building con-
fidence and providing an outline for the task at hand. “Problem Solving” sections
stress the importance of design and planning. “How To” guides help students with
common programming tasks. Numerous “Worked Examples” demonstrate how to
aPprpolbyl cehmap steorl vcoinncge psttsr atot eingtieerse satirneg mpraodblee mexs.p licit.
Practical, step-by-step illustrations of techniques help students devise and evaluate
solutions to programming problems. Introduced where they are most relevant, these

strategies address barriers to success for many students. Strategies included are:

• Algorithm Design (with pseudocode) • Stepwise Refinement

• First Do It By Hand (doing sample • Adapting Algorithms

calculations by hand)
• Discovering Algorithms by

• Flowcharts Manipulating Physical Objects

• Test Cases • Tracing Objects

• Hand-Tracing • Patterns for Object Data

• Storyboards • Thinking Recursively

• Solve a Simpler Problem First • Estimating the Running Time of
Practice makes perfect. an Algorithm
• Reusable Functions
Of course, programming students need to be able to implement nontrivial programs,
but they first need to have the confidence that they can succeed. Each section con-
tains numerous exercises that ask students to carry out progressively more complex
tasks: trace code and understand its effects, produce program snippets from prepared
parts, and complete simple programs. Additional review and programming problems
are provided at the end of each chapter.
iii
iv Preface

A visual approach motivates the reader and eases navigation.
Photographs present visual analogies that explain the o.
ot
h
nature and behavior of computer concepts. Step-by- p
k
c
step figures illustrate complex program operations. Sto
Syntax boxes and example tables present a variety er/i
or
of typical and special cases in a compact format. It pl
x
a
is easy to get the “lay of the land” by browsing the err
Fvioscuualss , obnef othree f oecsusseinngt ioanl sth we theixlteu able minagte rial. © T
technically accurate.
Visual features help the reader
with navigation.
An encyclopedic coverage is not helpful for a begin-
ning programmer, but neither is the opposite—
reducing the material to a list of simplistic bullet points. In this book, the essentials
are presented in digestible chunks, with separate notes that go deeper into good prac-
tices or language features when the reader is ready for the additional information.
New to This Edition

Interactive Learning
With this edition, interactive content is front and center. Immersive activities integrate
with this text and engage students in activities designed to foster in-depth learning.
Students don’t just watch animations and code traces, they work on generating them.
Live code samples invite the reader to experiment and to learn programming con-
structs first hand. The activities provide instant feedback to show students what
Ath eFyo dcidu rsi gohnt a Dnda wtah eSrcei tehnecy en eed to study more.

The methods of data science are becoming so important that students in many
disciplines, and not just computer scientists, are eager to learn the fundamentals of
programming. Python is uniquely positioned as the “go to” language for budding
data scientists, due to its logical structure, interactive programming libraries that
invite exploration, and a wealth of libraries for data manipulation.
This book employs a proven pedagogy for teaching programming that is not lim-
ited to computer science majors. In this edition, we provide additional examples and
eJuxesrtc itshees tRhaigt fhotc uAsm ono vuanrito uosf a Pspyethctos nof data science.

When we wrote this book, our goal was to teach good programming and computer
science, using Python as the means of instruction and not an end in itself.
Following suggestions of users of prior editions, we accelerated the coverage of
cMoonvreen Tieoncoel bopoexreatsio ns for working with strings and lists in this edition.

A popular enhancement of the previous edition was the introduction of optional
“Toolbox” sections that introduce useful packages in the wonderful ecosystem of
Python libraries. Students are empowered to perform useful work such as statistical
Preface v

computations, drawing graphs and charts, sending e-mail, processing spreadsheets,
and analyzing web pages. The libraries are placed in the context of computer sci-
ence principles, and students learn how those principles apply to solving real-world
problems. Each Toolbox is accompanied by many new end-of-chapter review and
programming exercises.
New to this edition are additional Toolboxes on turtle graphics and game
programming.
A Tour of the Book

Figure 1 shows the dependencies between the chapters and how topics are organized.
The core material of the book is Chapters 1–8. Chapters 9 and 10 cover object-
oriented programming, and Chapters 11 and 12 support a course that goes more
Appendices
deeply into algorithm design and analysis.
Six appendices provide a handy reference for students on operator
pGrreacpedheinccse ,a rnesde rIvmeda wgoer dPsr,o Ucneicsosdien, gth e Python standard library, and more.

Writing programs that create drawings or process images can provide students with
effective visualizations of complex topics. Chapter 2 introduces the EzGraphics
open-source library and how to use it to create basic graphical drawings. The library,

Fundamentals
1. Introduction
Object-Oriented Programming
Data Structures & Algorithms
2. Programming
with Numbers

and Strings

3. Decisions

4. Loops

A gentle
5. Functions introduction to recursion
is optional.

Sections 6.1 – 6.3
Sections 7.1 and 7.2 6.6 I.t eLriasttiso n (lists) can be covered
(text file processing) can be with Chapter 4.

covered with Chapter 4.

7. Files and 8. Sets and 9. Objects
Exceptions D6i.c tItioernaatriioens and Classes 11. Recursion

Figure 1 10. Inheritance 12. Sorting
and Searching
Chapter Dependencies
vi Preface

which students find easier to use than Python’s standard Tkinter library, also supports
simple image processing. Chapter 5 contains an optional Toolbox on turtle graphics.
Graphics Worked Examples and exercises are provided throughout the text, all of
wExheicrhc aisree osp tional.

End-of-chapter exercises contain a broad mix of review and programming questions,
with optional questions from graphics, science, and business. Designed to engage
sIntutdeernatcs,t tihvee eexTerecxiste sD ilelussitgrantee dth feo vra lPureo ogf praromgrmaminmgin Sg tiun dapepnlitesd fields.

wiley.com vitalsource.com
Available online through , , or at your local bookstore, the
interactive eText features integrated student coding activities that foster in-depth
learning. Designed by Cay Horstmann, these activities provide instant feedback to
show students what they did right and where they need to study more. Students do
http://wiley.
more than just watch animations and code traces; they work on generating them right
com/college/sc/horstmann
in the eText environment. For a preview of these activities, check out
.
Customized formats are also available in both print and digital formats and pro-
vide your students with curated content based on your unique syllabus.
Please contact your Wiley sales rep for more information about any of these
oWpetibon Rs.e sources

www.wiley.
com/go/pfe3
This book is complemented by a complete suite of online resources. Go to

to visit the online companion sites, which include
• Source code for all example programs, Toolboxes, and Worked Examples in the

book.

• Lecture presentation slides (for instructors only).
• Solutions to all end-of-chapter review and programming exercises (for instructors

only).
• A test bank that focuses on skills, not just terminology (for instructors only). This
extensive set of multiple-choice questions can be used with a word processor or

imported into a course management system.
®
• CodeCheck , an innovative online service that allows instructors to design their
own automatically graded programming exercises.
Walkthrough vii
A Walkthrough of the Learning Aids

The pedagogical elements in this book work together to focus on and reinforce key
concepts and fundamental principles of programming, with additional tips and detail
organized to support and deepen these fundamentals. In addition to traditional fea-
tures, such as chapter objectives and a wealth of exercises, each chapter contains ele-
ments geared to today’s visual learner.

1.5 Analyzing Your First Program 11

1.5 Analyzing Your First Program
In this section, we will analyze the first Python program in detail. Here again is the
manda Rohde/iStockphoto. scoed12ce 0:#p 4r /iMhntye( lf"liHroes.tlp lPyoy, t hWoonr lpdr!o"g)r am. statements
Throughout each chapter, © A bAe P #ty rtMahyno sfnlia rptsertod g Parynatdhmo en cx operncoutgatrieanmds. b oyn teh oer P mytohroen li innetse ropf rinetsetrru. Tchtieo nfisr sotr l ine that will
margin notes show where A comment provides comment #
information to the
new concepts are introduced programmer. itsiv ae informati.o Cno tmo mtheen tpsr boeggrianm wmitehr . Caonmdm aeren tnso wt isltla bteem deisnctus.s Tsehde yin p mroovridee d deetsacirl iipn-
and provide an outline of key ideas. SecpTtrhiioenn ts (2e"c.H1oe.n5lld. o l,i nWeo rclodn!t"a)in s a statement
A function is
ian csotrlulecctitoionns of that prints or displaypsr ai nlitn e of text, namely “Hello, World!”. In this statefumnecntito, nw e
that perform a call a function named and pass it the information to be displayed. A is
particular task. a collection of programming instructions that carry out a particular task. We do not
have to implement this function, it is part of the Python language. We simply want
Abfuy fn uscpntiecotcniiof nynia nimsg c eta hallene dd the1T f.ou unsceti,o onr tcoa pll,e ar ffournmct iitosn i ninte Pnydtehdo nta, ysko,u n naemeedl yto t osp perciinfyt :a pvrailnute.
its arguments. 2. The name of the function you want to usaer g(iunm theinst case, )". Hello, World!"
Annotated syntax boxes Any values the function needs to carry out its task (in this case, ).
The technical term for such a value is an . Arguments are enclosed in
provide a quick, visual overview parentheses; multiple arguments are separated by commas. The number of
arguments required depends on the function.
of new language constructs.
Syntax 1.1 print Statement

Syntax print()
print(value, value, ..., valuen)
1 2
Annotations explain required Aarlle a grigvuemne, nat bs laarnek o lpintieo nisa lp. rIifn ntoe da.r guments
components and point to more
print("The answer is", 6 + 7, "!")
information on common errors
The values to be printed,
or best practices associated one after the other,
separated by a blank space.
with the syntax.

Analogies to everyday objects are
used to explain the nature and behavior

of concepts such as variables, data

Like a variable in a computer types, loops, and more.
program, a parking space has
an identifier and a contents.
viii Walkthrough

Memorable photos reinforce

analogies and help students
remember the concepts. pie(fruit) pie(fruit)

A recipe for a fruit pie may say to use any
kind of fruit. Here, “fruit” is an example of a
parameter variable. Apples and cherries are
examples of arguments.

Problem Solving sections teach

techniques for generating ideas and 6.6 Problem Solving: Discovering Algorithms by Manipulating Physical Objects 311
evaluating proposed solutions, often
using pencil and paper or other
Now how does that help us with our problem, switching the first and the second
artifacts. These sections emphasize half of the list?
that most of the planning and problem Let’s put the first coin into place, by swapping it with the fifth coin. However, as
Python programmers, we will say that we swap the coins in positions 0 and 4:
solving that makes students successful
happens away from the computer.

HOW TO 1.1
Describing an Algorithm with Pseudocode How To guides give step-by-step
guidance for common programming
This is the first of many “How To” sections in this book that give you step-by-step proce-
dures for carrying out important tasks in developing computer programs. tasks, emphasizing planning and
Before you are ready to write a program in Python, you need to develop an algorithm—a
mPreothboledm fo rS atrartievminge natt a solution for a particular problem. Describe the algorithm in pseudo- testing. They answer the beginner’s
code: a sequence of precise steps formulated in English.
question, “Now what do I do?” and
You have the choice of buying two cars.
One is more fuel efficient than the other, but also more expensive. integrate key concepts into a
You know the price and fuel efficiency (in miles per gallon, mpg)
of both cars. You plan to keep the car for ten years. Assume a problem-solving sequence.
price of $4 per gallon of gas and usage of 15,000 miles per year.
You will pay cash for the car and not worry about financing costs. © David H. Lewis/Getty Images.
Which car is the better deal?
Step 1
Determine the inputs and outputs.
In opuurr cshaamsep lper ipcreo1b lemf, uweel e hffaivceie tnhceys1e inputs: Worked Examples apply
• WORKaEnDd EXAMPLE, the1 p.1ri ce and fuel efficiency (in mpg) of the first car
Writing an Algorithm for Tiling a Floor the steps in the How To to a
di erent example, showing
Problem Statement
Make a pla×n for tiling a rectangular bathroom floor with alternating how they can be used to
black and white tiles measuring 4 4 inches. The floor dimensions, measured in inches, are plan, implement, and test
Step 1 multiples of 4.
a solution to another
Determine the inputs and outputs. ×
The inputs are the floor dimensions (length width), programming problem.
Step 2 measured in inches. The output is a tiled floor.
Break down the problem into smaller tasks.
A natural subtask is to lay one row of tiles. If you can
solve that, then you can solve the problem by laying © kilukilu/Shutterstock.
one row next to the other, starting from a wall, until
you reach the opposite wall.
How do you lay a row? Start witEh a txile aat onmew widatllh. p/ 4le tables support beginners
If it is white, put a black one next to it. If it is black, put a white one next to it. Keep going until
Table1 NSutmepb 3e r Lyiotue rreaachls th ien o pPpoystithe woanll. The row willcontwaiinth mutilltes. iple,concrete examples.
Describe each subtask in pseudocode.
Number Type In tWPhlaehc iplCee s aoteh bmeula fdmlcookoe ctrnio liestd n ineo ,tt hy yeoe ntu fo iwlrltehadw,n retes ptteo cao btr tnehe mer .f oolrloew piTnrge csh isteeep as: bsoeu t texaabctlylweshe repthoe tiinlest ar oe pulatce cd.ommon
6 int Repeat this step width / 4 – 1 times: errors and present another quick
–6 int An integer has no fractional part. reference to the section’s topic.
0 int Integers can be negative.
0.5 float Zero is an integer. float

1.0 float A number with a fractional part has type flo. at
1E6 float An integer with a fractional part .0 has type .
6 float
2.96E-2 float AN unmumbebresr i inn e exxppoonneennttiiaall n noottaattiioonn a: 1lw ×a 1y0s hoarv e1 0ty0p0e0 00. . Optional graphics programming
100,000 ENrreogra: tive exponent: 2.96 × 10–2 = 2.96 / 100 = 0.0296 examples demonstrate constructs
3 1/2 Error: Do not use a comma as a decimal separator. with engaging drawings, visually
Do not use fractions; use decimal notation: 3.5. reinforcing programming concepts.