Python for Everyone

724 Pages·2013·95.239 MB·English

by  Cay S. Horstmann, Rance D. Necaise

HORSTMANN + NECAISE =
N H c Ay H O R S T M A N N
A WHOLE NEW WAY TO LEARN PROGRAMMING WITH PYTHON! e O
c R
A S
i T RANce D. NecAiSe
This exciting new text by Cay Horstmann and Rance Necaise provides an introduction to programming S
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e
using Python that focuses on the essentials and on the problem-solving skills all good programmers
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need to be successful. Suitable for a first course in programming for students in computer science,
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engineering, scientific, or liberal arts disciplines, it requires no prior programming experience.
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KEY FEATURES
• A visual approach motivates the reader and eases navigation. Abundant illustrations and
photographs make concepts memorable. Syntax boxes annotate code examples to present a visual
summary of key points.
• G uidance and worked examples help students succeed. Step-by-step “how-to” boxes guide p
students through the implementation of core concepts. Worked examples apply these steps to new y
problems. “Tips” and “Common Errors” boxes guide students to good practice. Python
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• Practice makes perfect. Abundant practice tools build student confidence and skills. Self checks H
in each section test understanding and point students to exercises they can do to practice what they
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learned.
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• Teaches computer science principles, not just Python. The core of the book builds students’
skills in control flow, loops, functions, lists, file I/O, sets, and dictionaries before addressing classes
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and inheritance. O
R F O R E V E R Y O N E
• A focus on problem solving. Problem-solving sections provide techniques for planning and

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evaluating solutions—before starting to code. These include the use of psuedocode for algorithm
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design, hand-tracing code segments, storyboards and more. E
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Y
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CAY S. HORSTMANN is a Professor of Computer Science in the Department of Computer Science at San
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Jose State University. He is an experienced professional programmer, having worked as Vice President
and Chief Technology Officer for an internet startup and as a consultant for major corporations, univer-
sities, and organizations. Horstmann is the author of many successful professional and academic books,
including Big Java, Big Java: Late Objects, Big C++, and C++ for Everyone —all with Wiley.
RANCE D. NECAISE is a member of the faculty in the Department of Computer Science at The College
of William and Mary. He has over 22 years of teaching experience across a broad range of the computer
science discipline. Necaise is also the author of Data Structures and Algorithms Using Python published
by Wiley and has authored numerous professional and pedagogical online tutorials and references.
Cover design: Madelyn Lesure
Cover image credits: castle: Anik Messier/Getty Images, cow: © Eric Isselee/Shutterstock,
hotair balloon: © Mikhail Mishchenko/123RF.com, trumpets: © modella/123RF.com,
ISBN 978-1-118-62613-9
trebuchet: © Stephen Coburn/123RF.com, parrot: © Eric Isselée/iStockphoto,
binoculars: © Tom Horyn/iStockphoto 90000
www.wiley.com/college/horstmann 9 781118 626139
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Variable and Constant Definitions Selected Operators and Their Precedence
(See Appendix B for the complete list.)
Name Initial value
[] Sequence element access
cansPerPack = 6
Use uppercase for constants ** Raising to a power
CAN_VOLUME = 0.335 * / // % Multiplication, division, floor
division, remainder
+ - Addition, subtraction
Mathematical Functions
< <= > >= != in Comparisons and membership
abs(x) Absolute value |x| not
round(x) Rounds to nearest integer or Boolean operators
max(x1, x2, ...) Largest of the arguments and
min(x1, x2, ...) Smallest of the arguments
From math module: Strings
sqrt(x) Square root x
trunc(x) Truncates to an integer s = "Hello"
sin(x), cos(x), tan(x) Sine, cosine, tangent of x len(s) The length of the string: 5
degrees(x), radians(x) Converts to degrees or radians s[1] The character with index 1: "e"
log(x), log(x, base) Natural log, log (x) s + "!" Concatenation: Hello!
base
s * 2 Replication: "HelloHello"
s.upper() Yields "HELLO"
Imports
s.replace("e", "3") Yields "H3llo"
Module Imported items
from math import sqrt, log
Lists
An empty list
friends = []
Conditional Statement
values = [16, 3, 2, 13]
Condition
for i in range(len(values))
if floor >= 13 : Executed when condition is true values[i] = i * i
actualFloor = floor - 1
Second condition (optional)
elif floor >= 0 : friends.append("Bob")
actualFloor = floor friends.insert(0, "Amy")
else : Executed when if "Amy" in friends :
print("Floor negative") all conditions are n = friends.index("Amy")

friends.pop(n)
false (optional) Removes nth
else :
friends.pop( ) Removes last
Loop Statements friends.remove("Bob")
Condition Concatenation
guests = friends + ["Lee", "Zoe"]
scores = [0] * 1 2 Replication
while balance < TARGET :
year = year + 1 Executed while bestFriends = f r i e n d s [ 0 : 3 ] Slice
balance = balance * (1 + rate / 100) condition is true Included Excluded

A container (list, str, range, dict, set) total = sum(val u e s ) List must contain numbers
for value in values : largest = max(v a l u e s )
sum = sum + value values.sort() Use min to get the smallest
Function Definition Tables
table = [[16, 3, 2, 13],
Function name Parameter name
[5, 10, 11, 8],
[9, 6, 7, 12],
def cubeVolume(sideLength) : Number of rows
[4, 15, 14, 1]]
volume = sideLength ** 3
Number of columns
return volume
for row in range(len(table)) :
Exits method and
for column in range(len(table[row])) :
returns result
sum = sum + table[row][column]
P y t h o n
f o r
E v E r y o n E
© Anik Messier/Getty Images.
Cay Horstmann
San Jose State University
Rance D. Necaise
College of William and Mary
pyt_fm.indd 1 1/31/13 6:40 PM
VP AND EXECUTIVE PUBLISHER Don Fowley
EXECUTIVE EDITOR Beth Lang Golub
EDITORIAL ASSISTANT Katherine Willis
EXECUTIVE MARKETING MANAGER Christopher Ruel
PRODUCTION MANAGEMENT SERVICES Cindy Johnson
CREATIVE DIRECTOR Harry Nolan
SENIOR DESIGNER Madelyn Lesure
PHOTO MANAGER Hilary Newman
SENIOR PHOTO EDITOR Lisa Gee
COVER CREDIT Based on Monty Python and the Holy Grail.
Reproduced with permission of Python (Monty)
Pictures, Ltd.
COVER PHOTOS (balloon) © Mikhail Mishchenko/123RF.com;
(binoculars) © Tom Horyn/iStockphoto;
(castle) © Anik Messier/Getty Images;
(cow) © Eric Isselée/Shutterstock;
(parrot) © Eric Isselée/iStockphoto;
(trebuchet) © Stephen Coburn/123RF.com;
(trumpets) © modella/123RF.com.
This book was set in Stempel Garamond by Publishing Services, and printed and bound by Quad/Graphics.
The cover was printed by Quad/Graphics.
This book is printed on acid-free paper. ∞
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ISBN 978-1-118-62613-9
ISBN 978-1-118-64520-8 (BRV)
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
pyt_fm.indd 2 1/31/13 6:40 PM
For Clora, maybe—C.H.
To my parents
Willard and Ella—R.N.
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pyt_fm.indd 4 1/31/13 9:43 AM
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.
Here are the book’s key features:
Present fundamentals first.
The book takes a traditional route, first stressing control structures, functions, proce-
dural decomposition, and the built-in data structures. Objects are used when appro-
priate in the early chapters. Students start designing and implementing their own
classes in Chapter 9.
Guidance and worked 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 instruc-
tions. However, step-by-step guidance is immensely helpful for building confidence
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 apply chapter
concepts to interesting problems.
Practice makes perfect.
Of course, programming students need to be able to implement nontrivial programs,
but they first need to have the confidence that they can succeed. This book contains
a substantial number of self-check questions at the end of each section. “Practice It”
pointers suggest exercises to try after each section. A bank of quiz and test questions
covering computer science concepts and programming skills is available to instructors.
A visual approach motivates the reader and eases navigation.
Photographs present visual analogies that explain the
nature and behavior of computer concepts. Step-by-
step figures illustrate complex program operations.
Syntax boxes and example tables present a variety
of typical and special cases in a compact format. It
is easy to get the “lay of the land” by browsing the
visuals, before focusing on the textual material.
Focus on the essentials while being
technically accurate.
Visual features help the reader
An encyclopedic coverage is not helpful for a begin- with navigation.
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.
© Terraxplorer/iStockphoto.
v
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vi Preface
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:
chapter 1. Introduction
chapter 2. Programming with Numbers and Strings
chapter 3. Decisions
chapter 4. Loops
chapter 5. Functions
chapter 6. Lists
chapter 7. Files and Exceptions
chapter 8. Sets and Dictionaries
Two chapters cover object-oriented programming:
chapter 9. Objects and Classes
chapter 10. Inheritance
Two chapters support a course that goes more deeply into algorithm design and
analysis:
chapter 11. Recursion
chapter 12. Sorting and Searching
Any chapters can be incorporated into a custom print version of this text; ask your
Wiley sales representative for details.
Appendices  Five appendices provide a handy reference for students:
appendix a. The Basic Latin and Latin-1 Subsets of Unicode
appendix B. Python Operator Summary
appendix c. Python Reserved Word Summary
appendix D. The Python Library
appendix E. Binary Numbers and Bit Operations
Problem Solving Strategies
Throughout the book, students will find practical, step-by-step guidance to help
them 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) • Adapting Algorithms
• First Do It By Hand (doing sample • Discovering Algorithms by
calculations by hand) Manipulating Physical Objects
• Flowcharts • Tracing Objects (identifying state
• Test Cases and behavior)
• Hand-Tracing • Patterns for Object Data
• Storyboards • Thinking Recursively
• Reusable Functions • Estimating the Running Time of
• Stepwise Refinement an Algorithm
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Preface  vii
An Optional Graphics Library
Writing programs that create drawings can provide students with effective visualiza-
tions of complex topics. We provide a very simple graphics library that we introduce
in Chapter 2. Subsequent chapters contain worked examples and exercises that use
the library. This material is completely optional.
Exercises
End-of-chapter exercises contain a broad mix of review and programming ques-
tions, with optional questions from the domains of graphics, science, and business.
Designed to engage students, the exercises illustrate the value of programming in
applied fields.
Web Resources
This book is complemented by a complete suite of online resources. Go to www.wiley.
com/college/horstmann to visit the online companion sites, which include
• Source code for all examples in the book.
• Lecture presentation slides (in PowerPoint format).
• Solutions to all review and programming exercises (for instructors only).
• A test bank that focuses on skills, not just terminology (for instructors only).
Fundamentals
1. Introduction
Object-Oriented Programming
Data Structures & Algorithms
2. Programming
with Numbers
and Strings
3. Decisions
4. Loops
A gentle
introduction to recursion
5. Functions is optional.
Sections 7.1 and 7.2
(text file processing) can be
6.6 I.t eLriasttison
covered with Chapter 4.
7. Files and 8. Sets and 9. Objects
Exceptions D6i.c Ittieornaatrioiens and Classes 11. Recursion
Figure 1  
Chapter   10. Inheritance 12. Sorting
and Searching
Dependencies
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viii Walkthrough
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
code:
ch01/hello.py
1 # My first Python program.
2 print("Hello, World!")
A Python program contains one or more lines of instructions or statements that will
be translated and executed by the Python interpreter. The first line
Throughout each chapter,
# My first Python program.
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new concepts are introduced the programmer. Section 2.1.5.
The second line contains a statement
and provide an outline of key ideas.
print("Hello, World!")
that prints or displays a line of text, namely “Hello, World!”. In this statement, we
Aa cfuonllectcitoionn i so f call a function named print and pass it the information to be displayed. A function is
instructions a collection of programming instructions that carry out a particular task. We do not
that perform a have to implement this function, it is part of the Python language. We simply want
particular task. the function to perform its intended task, namely to print a value.
To use, or call, a function in Python, you need to specify
A function is called
bfuyn scptieocnif nyianmge t haen d 1. The name of the function you want to use (in this case, print).
its arguments. 2. Any values the function needs to carry out its task (in this case, "Hello, World!").
The technical term for such a value is an argument. Arguments are enclosed in
Annotated syntax boxes parentheses with multiple arguments separated by commas. The number of
provide a quick, visual overview arguments required depends on the function.
of new language constructs.
Syntax 1.1 print Statement
Syntax print()
print(value1, value2, ..., valuen)
All arguments are optional. If no arguments
Annotations explain required are given, a blank line is printed.
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.
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