2. Winner, Software Development Magazine’s
1996 Jolt Award for Best Book of the Year
“This book is a tremendous achievement. You owe it to yourself to
have a copy on your shelf. The chapter on iostreams is the most
comprehensive and understandable treatment of that subject I’ve
seen to date.”
Al Stevens
Contributing Editor, Doctor Dobbs Journal
“Eckel’s book is the only one to so clearly explain how to rethink
program construction for object orientation. That the book is also
an excellent tutorial on the ins and outs of C++ is an added bonus.”
Andrew Binstock
Editor, Unix Review
“Bruce continues to amaze me with his insight into C++, and
Thinking in C++ is his best collection of ideas yet. If you want clear
answers to difficult questions about C++, buy this outstanding
book.”
Gary Entsminger
Author, The Tao of Objects
“Thinking in C++ patiently and methodically explores the issues of
when and how to use inlines, references, operator overloading,
inheritance and dynamic objects, as well as advanced topics such as
the proper use of templates, exceptions and multiple inheritance.
The entire effort is woven in a fabric that includes Eckel’s own
philosophy of object and program design. A must for every C++
developer’s bookshelf, Thinking in C++ is the one C++ book you
must have if you’re doing serious development with C++.”
Richard Hale Shaw
Contributing Editor, PC Magazine
3. whenever possible, and to that effect, “Thinking in C++” has given me the strong
Comments from Readers: foundation for my continuous improvement. Peter Tran, Senior Systems
Analyst (IM), Compaq Computer Corporation
Wonderful book … Great stuff! Andrew Schulman, Doctor Dobbs Journal
This book is the best general reference in my on-going quest to master C++. Most
An absolute, unqualified must. One of the most-used, most trusted books on my books explain some topics thoroughly but are deficient in others. “Thinking in
shelf.” TUG Lines C++” 2/E does not pass the buck to another book. When I have questions it has
This is stuff a programmer can really use. IEEE Computer answers. Thomas Michel
A refreshing departure. PJ Plauger, Embedded Systems Programming I have a whole mountain of books and none of them make sense nor do they
magazine explain things properly. I have been dying for a good template and STL book.
Then I decided to read your material and I was amazed. What you did was show
…Eckel succeeds … it’s so readable. Unix World how to write C++ with templates and STL without bogging down with details.
What you did was what I expected of the C++ community, the next generation of
Should definitely be your first buy. C Gazette C++ authors. As an author I AM IMPRESSED at your writing and explanation
A fantastic reference for C++! Michael Brandt, Senior Analyst/Programmer, skills. You covered topics that nobody has properly covered before. Your
Sydney, Australia approach is one from a person who has actually sat down and went through the
material in detail. And then you questioned the sanity of the situation and what
On our project at HRB Systems we call your book “The Answer Book”. It is our would be the problem areas. On my bookshelf, it will definitely be one of the
C++ Bible for the project. Curt Snyder, HRB Systems necessary books, right beside Petzold. Christian Gross, consultant/mentor
Your book is really great, and I can’t thank you enough for making it available for cgross@eusoft.com
free on the web. It’s one of the most thorough and useful references for C++ I’ve I think your book is very, very, VERY good. I have compared it to others in the
seen. Russell Davis bookstore, and have found that your book actually teaches me basic C++
... the only book out there that even comes close to being actually readable when fundamentals while I learn the STL... a very nice experience to learn about both
trying to learn the ropes of C++ (and the basics of good object oriented at once, hand-in-hand. I think your book is laid out very well, and explains things
programming in general). Gunther Schulz, KawaiiSoft in an easy-to-understand fashion. Jeff Meininger, Software Developer,
boxybutgood.com
I love the examples in your book. There’s stuff there that I never would have
thought of (and some things that I didn’t know you could do)! Rich Herrick, Your book is the best by far of any I’ve seen. Please get it right so that we can all
Senior Associate Software Engineer, Lockheed-Martin Federal Systems, have an excellent and “reliable” reference work! And please hurry! We are
Owego, NY desperate for a work of this quality! Steve Strickland, Live Minds (a Puzzle
business)
It’s an amazing book. Any questions I have I refer to this online book. Helped in
every case. I’m simply happy to have access to a book of this caliber. Wes Kells, (On Usenet) Unlike most other C++ authors, Eckel has made a career of teaching
C++ and Java classes ONLY. He’s had the benefit of a GREAT deal of novice
Comp Eng. Student, SLC Kingston.
feedback, and the books reflect that. His books are not just about writing in
You are an invaluable resource and I greatly appreciate your books, email list C++/Java, but understanding the intent of the languages and the mindset that
etc... It seems every project I have worked on has been successful because of your goes with thinking in them. Eckel’s also the best technical writer I’ve read since
insights. Justin Voshell Jeff Duntemann. Very clear and easy to read. Don’t be put off by the apparent
large size of his books. Either can be read in *less* than 21 days. :-} Randy
This is the book I have been looking for on C++. Thomas A. Fink, Managing
Crawford, MRJ Technology Solutions, Fairfax VA
Director, Trepp, LLC
Your work is greatly appreciated and I thank you for helping me understand both
Your books are authoritative yet easy to read. To my colleagues I call you the
C++ and Java better. Barry Wallin, Math/Computer Science Teacher,
K&R of C++. Mark Orlassino, Senior Design Engineer, Harmon
Rosemount High School, Rosemount, MN
Industries, Inc., Hauppauge, NY
When I first started learning C++, your book “Thinking in C++” was my shining
guide light in a dark tunnel. It has been my endeavor to improve my C++ skills
4. I would like to thank you for your book “Thinking in C++” which is, with no
doubt, the best book I ever read about this subject. Riccardo Tarli - SW
Engineer - R&D TXT Ingegneria Informatica - Italy
Thinking
I have been reading both of your books, Thinking In Java and Thinking In C++.
Each of these books is easily the best in its category. Ranakarprasad H. Tiwari,
Mumbai, India
… the “Debugging Hints” section is so valuable, I’m tempted to print it and keep
it with me at all times. I think this section should be a mandatory part of any
introductory class after the first one or two programming problems. Fred
Ballard, Synectics Inc.
In
Your book is really a treasure trove of C++ knowledge. I feel like you give a good
overview and then explain the nuts and bolts. Raymond Pickles, Antenna
Section, Radar Division, U.S. Naval Research Laboratory, Washington
DC
As an Internal Medicine Specialist and Computer Scientist I spend a great deal of
time trying to extract information from books and journals. My experience is that
C++
a good author is one who makes difficult concepts accessible, a great one makes it
look almost easy. On this score you are certainly one of my top three technical
writers. Keep up the good work. Dr. Declan O’Kane, Leicester, England
For my second-level C++ course, “Thinking in C++” is my constant reference and
companion, and I urge my students to consult it regularly. I refer to the chapter
on Operator Overloading constantly. The examples/code alone are worth the cost
of the book many times over. So many books and development environments are
predicated on the assumption that the only application for a programming
language is for a Windows environment; it’s great to find and use a book which
Second Edition
concentrates on C++ so we can prepare our students for careers in fields like
embedded systems, networking, etc., which require real depth of understanding.
Robert Chase, Professor, Sweet Briar College
I think it’s a fantastic intro to C++, especially for longtime dabblers like me – I Bruce Eckel
often know “how,” but rarely “why,” and TIC2 is a godsend. Tony Likhite,
System Administrator/DBA, Together Networks President, MindView Inc.
After reading the first 80 pages of this book, I have a better understanding of oop
then I've gotten out of the ton of books I've accumulated on the subject. Thanks...
Rick Schneewind
Prentice Hall
Upper Saddle River, New Jersey 07458
http://www.prenhall.com
6. Dedication
To my parents, my sister, and my brother
Seminars-on-CD-ROM
If you like the Thinking in C
Seminar-on-CD packaged with
this book, then you’ll also like:
ruce Eckel’s
ands-On C++ Seminar
Multimedia CD ROM
t’s like coming to the seminar!
vailable at www.BruceEckel.com
Overhead slides and synchronized audio recorded by Bruce Eckel
All the lectures from the Hands-On C++ Seminar
Based on this book
Get a solid grounding in Standard C++ Fundamentals
Just play it to see and hear the lectures!
Lectures are indexed so you can rapidly locate the discussion
of any subject
Details and sample lecture can be found on the Web site
ee www.BruceEckel.com
or other Seminars-on-CD ROM
The Intermediate C++ Seminar
Advanced C++ Topics
7. What’s inside...
Preface 1 1: Introduction to
What’s new in Objects 21
the second edition .... 2 The progress of
What’s in Volume 2
of this book......................... 3 abstraction............. 22
How to get Volume 2............ 3 An object has an
Prerequisites............ 3 interface ................ 25
Learning C++ .......... 4 The hidden
Goals ...................... 5 implementation ...... 28
Chapters ................. 7 Reusing the
Exercises............... 12 implementation ...... 29
Exercise solutions ...............12
Inheritance: reusing
Source code........... 12
the interface .......... 31
Language Is-a vs. is-like-a
standards .............. 14 relationships...................... 35
Language support ...............15 Interchangeable
The book’s objects with
CD ROM ................ 15 polymorphism ........ 37
CD ROMs, seminars, Creating and
and consulting ....... 16 destroying objects... 41
Errors ................... 16 Exception handling:
About the cover...... 17 dealing with errors .. 43
Book design and Analysis
production ............. 18 and design ............. 44
Acknowledgements . 19 Phase 0: Make a plan.......... 47
Phase 1: What are
we making?....................... 48
Phase 2: How will
we build it? ....................... 52
Phase 3: Build the core ....... 56
Phase 4: Iterate
the use cases .................... 57
8. Phase 5: Evolution ..............58 Modifying the
Plans pay off ......................60
More about outside object .................. 137
Function
Extreme iostreams .............. 96 Introduction to addresses ............ 198
Character array C++ references ................ 140 Defining a
programming ......... 61 concatenation .................... 96 Pointers and references function pointer ............... 198
Write tests first...................61 Reading input .................... 97 as modifiers ..................... 141 Complicated declarations
Pair programming ...............63 Calling other programs........ 98 & definitions .................... 199
Scoping................143 Using a function pointer .... 200
Why C++ Introducing Defining variables
Arrays of pointers
on the fly......................... 145
succeeds ............... 64 strings................... 98 to functions ..................... 201
A better C ..........................65
Reading and Specifying storage Make: managing
You’re already on
the learning curve...............65 writing files .......... 100 allocation .............147 separate
Global variables ................ 147
Efficiency ...........................66
Systems are easier to
Introducing Local variables ................. 149 compilation .......... 202
static .............................. 149 Make activities ................. 204
express and understand.......66 vector ................. 102 extern ............................. 151 Makefiles in this book ....... 207
Maximal leverage
with libraries ......................67
Summary............. 108 Constants ........................ 153 An example makefile ........ 208
volatile ............................ 155
Source-code reuse Exercises ............. 109 Summary............. 210
with templates ...................67 Operators and Exercises ............. 210
Error handling ....................67
Programming in the large.....68 3: The C in C++ 111 their use ..............156
Assignment ...................... 156
Strategies for Creating Mathematical operators ..... 156 4: Data Abstraction 217
Relational operators .......... 158
transition............... 68 functions ............. 112 Logical operators .............. 158 A tiny C-like
Guidelines..........................69 Function return values ...... 115
Management obstacles ........71 Using the C
Bitwise operators .............. 159 library ................. 219
Shift operators ................. 160 Dynamic
Summary .............. 73 function library ................ 116 Unary operators................ 163 storage allocation............. 223
Creating your own The ternary operator ......... 164 Bad guesses .................... 227
libraries with the librarian.. 117 The comma operator ......... 165
2: Making & Using Controlling Common pitfalls What's wrong?...... 229
Objects 75 execution............. 117
when using operators ........ 166 The basic object.... 230
Casting operators ............. 166
True and false ................. 117 C++ explicit casts............. 167 What's an object? . 238
The process of if-else ............................. 118 sizeof – an operator Abstract
language while .............................. 119 by itself ........................... 172
do-while ......................... 120 The asm keyword ............. 173 data typing .......... 239
translation ............. 76 for ................................. 121
Interpreters .......................77 The break and
Explicit operators .............. 173 Object details ....... 240
Compilers ..........................77 continue keywords ........... 122 Composite type Header file
The compilation process.......79 switch............................. 123 creation ...............174 etiquette.............. 241
Tools for separate Using and misusing goto ... 125 Aliasing names Importance of
Recursion........................ 126 with typedef..................... 174
compilation............ 80 header files ..................... 242
Declarations vs. definitions...81 Introduction to Combining variables The multiple-declaration
with struct ....................... 175 problem .......................... 244
Linking ..............................87 operators ............. 127 Clarifying programs The preprocessor directives
Using libraries ....................88 Precedence...................... 127 with enum ....................... 179 #define, #ifdef,
Your first Auto increment Saving memory and #endif ...................... 245
and decrement ................ 128 with union ....................... 181
C++ program ........ 90 A standard for header files 246
Using the iostreams class.....90 Introduction to Arrays ............................. 182 Namespaces in headers .... 247
Namespaces.......................91 data types ........... 129 Debugging hints ....193 Using headers in projects .. 248
Fundamentals of Basic built-in types ........... 129 Debugging flags................ 194 Nested structures.. 248
program structure...............93 bool, true, & false ............ 131 Turning variables and Global scope resolution ..... 253
"Hello, world!" ....................94 Specifiers ........................ 132 expressions into strings ..... 196
Running the compiler ..........95 Introduction to pointers .... 133 The C assert( ) macro........ 197 Summary............. 253
9. Returning by const value ... 345 Other storage
Exercises..............254 Aggregate Passing and returning class specifiers................. 414
initialization ......... 301 addresses ........................ 349
Namespaces......... 414
5: Hiding the Default Classes ................352 Creating a namespace ...... 415
const in classes ................ 353 Using a namespace .......... 417
Implementation 259 constructors ......... 304 Compile-time constants The use of namespaces ..... 422
Setting limits ........260 Summary............. 305 in classes......................... 356
Static members
const objects &
C++ access Exercises ............. 306 member functions ............. 359 in C++ ................ 423
Defining storage for
control .................261 volatile.................365
protected......................... 263 7: Function Overloading Summary .............367
static data members ......... 424
Nested and local classes.... 428
Friends.................263 & Default Exercises..............367 static member functions .... 429
Nested friends .................. 266 Static initialization
Is it pure?........................ 269 Arguments 309
Object layout ........269 9: Inline Functions 371 dependency ......... 432
More name What to do ...................... 434
The class ..............270 decoration ........... 311 Preprocessor Alternate linkage
Modifying Stash to use Overloading on
access control .................. 273 return values ................... 312
pitfalls .................372 specifications........ 442
Modifying Stack to use Macros and access ............ 376
Type-safe linkage ............. 313 Summary............. 443
access control .................. 274
Overloading Inline functions .....377
Handle classes ......275 Inlines inside classes ......... 378 Exercises ............. 443
Hiding the example .............. 314 Access functions ............... 379
implementation ................ 276
Reducing recompilation...... 276
unions ................. 318 Stash & Stack 11: References & the
Default with inlines ...........385 Copy-Constructor 449
Summary .............279
arguments ........... 321 Inlines &
Exercises..............280 Placeholder arguments...... 323 Pointers in C++ .... 450
the compiler .........390
Choosing overloading Limitations....................... 390 References
6: Initialization & vs. default Forward references ........... 391 in C++ ................ 451
Hidden activities in References in functions ..... 452
Cleanup 283 arguments ........... 324 constructors & Argument-passing
destructors ...................... 392
Guaranteed Summary............. 329 guidelines ....................... 455
Exercises ............. 330 Reducing clutter ....393 The copy-
initialization with the
More preprocessor constructor .......... 455
constructor ...........285
8: Constants 333 features ...............395 Passing & returning
Guaranteed cleanup Token pasting .................. 396 by value.......................... 455
Copy-construction ............ 462
with the Value substitution . 334 Improved error Default copy-constructor ... 468
const in header files ......... 335
destructor ............287 Safety consts................... 336 checking ..............396 Alternatives to copy-
construction .................... 471
Elimination of the Aggregates...................... 337 Summary .............400
definition block......289 Differences with C ............ 338 Pointers
Exercises..............400
for loops .......................... 291 Pointers ............... 340 to members ......... 473
Storage allocation ............. 292 Pointer to const ............... 340 Functions ........................ 475
Stash with const pointer ................... 341 10: Name Control 405 Summary............. 478
Assignment and
constructors and type checking .................. 343 Static elements Exercises ............. 479
destructors ...........294 Function arguments & from C .................406
static variables
Stack with constructors return values........ 344 inside functions ................ 406
Passing by const value ...... 344
& destructors ........298 Controlling linkage ............ 412
10. Stash for pointers ............ 558
12: Operator Choosing composition Abstract base classes
new & delete vs. inheritance ......604 and pure virtual
Overloading 485 for arrays............. 563 Subtyping ........................ 606
functions ............. 646
Warning & Making a pointer private inheritance ............ 609
Pure virtual definitions ...... 651
more like an array............ 564
reassurance ..........486 protected .............610 Inheritance and
Running out protected inheritance ........ 611
Syntax .................487 the VTABLE .......... 652
of storage ............ 565 Operator overloading
Overloadable Object slicing................... 655
Overloading & inheritance ........612 Overloading &
operators .............488
Unary operators................ 489 new & delete ........ 566 Multiple overriding ............ 658
Overloading global
Binary operators ............... 493
new & delete ................... 568
inheritance ...........613 Variant return type........... 660
Arguments &
return values.................... 505 Overloading Incremental virtual functions &
new & delete for a class .... 570
Unusual operators............. 508
Overloading
development.........614 constructors ......... 662
Operators you Order of constructor calls .. 663
can’t overload .................. 517 new & delete for arrays..... 573 Upcasting .............615 Behavior of virtual functions
Constructor calls .............. 576 Why “upcasting?”.............. 617
Non-member placement new & delete .... 577 Upcasting and the
inside constructors ........... 664
operators .............518 Summary............. 580 copy-constructor............... 617 Destructors and
Composition vs.
Basic guidelines ................ 520
Exercises ............. 580 inheritance (revisited) ....... 620
virtual destructors. 665
Overloading Pointer & reference
Pure virtual destructors..... 668
Virtuals in destructors....... 670
assignment...........521 upcasting......................... 622
Behavior of operator= ....... 522
14: Inheritance & A crisis ............................ 622
Creating an
object-based hierarchy ..... 671
Automatic type Composition 583 Summary .............623 Operator
conversion............533 Composition Exercises..............623 overloading .......... 675
Constructor conversion ...... 534
Operator conversion.......... 535 syntax................. 584 Downcasting ........ 678
Type conversion example... 538 Inheritance 15: Polymorphism & Summary............. 681
Pitfalls in automatic
type conversion ................ 539 syntax................. 586 Virtual Functions 627 Exercises ............. 682
Summary .............542 The constructor Evolution of C++
Exercises..............542 initializer list ........ 588 programmers ........628 16: Introduction to
Member object
initialization..................... 589
Upcasting .............629 Templates 689
13: Dynamic Built-in types in the The problem .........631 Containers ........... 690
initializer list.................... 589 Function call binding ......... 631
Object Creation 547 Combining composition virtual functions ....632
The need for containers .... 692
Overview
Object creation......549 & inheritance........ 591 Extensibility ..................... 633
C’s approach to the heap ... 550 Order of constructor & How C++ implements of templates......... 693
operator new.................... 552 The template solution ....... 696
destructor calls ................ 592
operator delete................. 553 late binding ..........636 Template syntax ... 697
A simple example ............. 553 Name hiding......... 595 Storing type information .... 637
Non-inline
Picturing virtual functions... 639
Memory manager Functions that Under the hood ................ 642
function definitions ........... 699
overhead ......................... 554 IntStack as a template...... 701
don’t automatically Installing the vpointer ....... 643
Early examples Objects are different ......... 644
Constants in templates ..... 703
inherit ................. 600 Stack and Stash
redesigned ...........555 Inheritance and static Why virtual
delete void* is member functions ............ 604
functions?.............645 as templates ........ 705
probably a bug ................. 555 Templatized pointer Stash . 707
Cleanup responsibility
with pointers .................... 557 Turning ownership
11. on and off.............713
Holding objects
by value ...............716
Introducing
iterators ...............719
Stack with iterators ........... 728
PStash with iterators ......... 732
Why iterators? ......738
Function templates............ 742
Summary .............743
Exercises..............744
A: Coding Style 747
B: Programming
Guidelines 759
C: Recommended
Reading 775
C.........................776
General C++.........776
My own list of books.......... 777
Depth &
dark corners .........778
Analysis & design ..779
Index 783
Preface
Like any human language, C++ provides a way to
express concepts. If successful, this medium of
expression will be significantly easier and more flexible
than the alternatives as problems grow larger and more
complex.
12. You can’t just look at C++ as a collection of features; some of the on a day-to-day basis but that the C++ and Java languages steer you
features make no sense in isolation. You can only use the sum of the away from (or even eliminate, in the case of Java).
parts if you are thinking about design, not simply coding. And to
understand C++ this way, you must understand the problems with So the short answer to the question “what’s different in the 2nd
C and with programming in general. This book discusses edition?” is: what isn’t brand new has been rewritten, sometimes to
programming problems, why they are problems, and the approach the point where you wouldn’t recognize the original examples and
C++ has taken to solve such problems. Thus, the set of features I material.
explain in each chapter will be based on the way that I see a
particular type of problem being solved with the language. In this What’s in Volume 2 of this book
way I hope to move you, a little at a time, from understanding C to
the point where the C++ mindset becomes your native tongue. The completion of the C++ Standard also added a number of
important new libraries, such as string and the containers and
Throughout, I’ll be taking the attitude that you want to build a algorithms in the Standard C++ Library, as well as new complexity
model in your head that allows you to understand the language all in templates. These and other more advanced topics have been
the way down to the bare metal; if you encounter a puzzle, you’ll be relegated to Volume 2 of this book, including issues such as
able to feed it to your model and deduce the answer. I will try to multiple inheritance, exception handling, design patterns, and
convey to you the insights that have rearranged my brain to make topics about building and debugging stable systems.
me start “thinking in C++.”
How to get Volume 2
Just like the book you currently hold, Thinking in C++, Volume 2 is
What’s new in the second edition downloadable in its entirety from my Web site at
This book is a thorough rewrite of the first edition to reflect all of www.BruceEckel.com. You can find information on the Web site
the changes introduced in C++ by the finalization of the C++ about the expected print date of Volume 2.
Standard, and also to reflect what I’ve learned since writing the first
edition. The entire text present in the first edition has been The Web site also contains the source code for both of the books,
examined and rewritten, sometimes removing old examples, often along with updates and information about other seminars-on-CD
changing existing examples and adding new ones, and adding many ROM that MindView, Inc. offers, public seminars, and in-house
new exercises. Significant rearrangement and re-ordering of the training, consulting, mentoring, and walkthroughs.
material took place to reflect the availability of better tools and my
improved understanding of how people learn C++. A new chapter
was added which is a rapid introduction to the C concepts and basic Prerequisites
C++ features for those who don’t have the C background to tackle
In the first edition of this book, I decided to assume that someone
the rest of the book. The CD ROM bound into the back of the book
else had taught you C and that you have at least a reading level of
contains a seminar that is an even gentler introduction to the C
comfort with it. My primary focus was on simplifying what I found
concepts necessary to understand C++ (or Java). It was created by
difficult: the C++ language. In this edition I have added a chapter
Chuck Allison for my company (MindView, Inc.), and it’s called
that is a rapid introduction to C, along with the Thinking in C
“Thinking in C: Foundations for Java and C++.” It introduces you to
seminar-on-CD, but I am still assuming that you already have some
the aspects of C that are necessary for you to move on to C++ or
kind of programming experience. In addition, just as you learn
Java, leaving out the nasty bits that C programmers must deal with
2 Thinking in C++ www.BruceEckel.com Preface 3
13. many new words intuitively by seeing them in context in a novel, it’s issues. I found out, by creating and chairing the C++ and Java
possible to learn a great deal about C from the context in which it is tracks at the Software Development Conference for many years,
used in the rest of the book. that I and other speakers tended to give the typical audience too
many topics, too fast. So eventually, through both variety in the
audience level and the way that I presented the material, I would
Learning C++ end up losing some portion of the audience. Maybe it’s asking too
much, but because I am one of those people resistant to traditional
I clawed my way into C++ from exactly the same position I expect lecturing (and for most people, I believe, such resistance results
many of the readers of this book are in: as a programmer with a from boredom), I wanted to try to keep everyone up to speed.
very no-nonsense, nuts-and-bolts attitude about programming.
Worse, my background and experience was in hardware-level For a time, I was creating a number of different presentations in
embedded programming, in which C has often been considered a fairly short order. Thus, I ended up learning by experiment and
high-level language and an inefficient overkill for pushing bits iteration (a technique that also works well in C++ program design).
around. I discovered later that I wasn’t even a very good C Eventually I developed a course using everything I had learned
programmer, hiding my ignorance of structures, malloc( ) and from my teaching experience. It tackles the learning problem in
free( ), setjmp( ) and longjmp( ), and other “sophisticated” discrete, easy-to-digest steps and for a hands-on seminar (the ideal
concepts, scuttling away in shame when the subjects came up in learning situation) there are exercises following each of the
conversation instead of reaching out for new knowledge. presentations. You can find out about my public seminars at
www.BruceEckel.com, and you can also learn about the seminars
When I began my struggle to understand C++, the only decent book that I’ve turned into CD ROMs.
was Bjarne Stroustrup’s self-professed “expert’s guide,1” so I was
left to simplify the basic concepts on my own. This resulted in my The first edition of this book developed over the course of two years,
first C++ book,2 which was essentially a brain dump of my and the material in this book has been road-tested in many forms in
experience. That was designed as a reader’s guide to bring many different seminars. The feedback that I’ve gotten from each
programmers into C and C++ at the same time. Both editions3 of seminar has helped me change and refocus the material until I feel
the book garnered enthusiastic response. it works well as a teaching medium. But it isn’t just a seminar
handout; I tried to pack as much information as I could within
At about the same time that Using C++ came out, I began teaching these pages, and structure it to draw you through onto the next
the language in seminars and presentations. Teaching C++ (and subject. More than anything, the book is designed to serve the
later, Java) became my profession; I’ve seen nodding heads, blank solitary reader who is struggling with a new programming language.
faces, and puzzled expressions in audiences all over the world since
1989. As I began giving in-house training to smaller groups of
people, I discovered something during the exercises. Even those
people who were smiling and nodding were confused about many Goals
My goals in this book are to:
1 Bjarne Stroustrup, The C++ Programming Language, Addison-Wesley, 1986 (first
1. Present the material one simple step at a time, so the reader
edition).
2 Using C++, Osborne/McGraw-Hill 1989.
can easily digest each concept before moving on.
3 Using C++ and C++ Inside & Out, Osborne/McGraw-Hill 1993.
4 Thinking in C++ www.BruceEckel.com Preface 5
14. 2. Use examples that are as simple and short as possible. This 7. I’ve tried not to use any particular vendor’s version of C++
often prevents me from tackling “real world” problems, but because, for learning the language, I don’t think that the
I’ve found that beginners are usually happier when they can details of a particular implementation are as important as the
understand every detail of an example rather than being language itself. Most vendors’ documentation concerning
impressed by the scope of the problem it solves. Also, there’s their own implementation specifics is adequate.
a severe limit to the amount of code that can be absorbed in a
classroom situation. For this I sometimes receive criticism for
using “toy examples,” but I’m willing to accept that in favor of Chapters
producing something pedagogically useful. C++ is a language in which new and different features are built on
3. Carefully sequence the presentation of features so that you top of an existing syntax. (Because of this, it is referred to as a
aren’t seeing something you haven’t been exposed to. Of hybrid object-oriented programming language.) As more people
course, this isn’t always possible; in those situations, a brief pass through the learning curve, we’ve begun to get a feel for the
introductory description will be given. way programmers move through the stages of the C++ language
features. Because it appears to be the natural progression of the
4. Give you what I think is important for you to understand procedurally-trained mind, I decided to understand and follow this
about the language, rather than everything that I know. I same path and accelerate the process by posing and answering the
believe there is an “information importance hierarchy,” and questions that came to me as I learned the language and those
there are some facts that 95 percent of programmers will questions that came from audiences as I taught the language.
never need to know and that would just confuse them and
add to their perception of the complexity of the language. To This course was designed with one thing in mind: to streamline the
take an example from C, if you memorize the operator process of learning C++. Audience feedback helped me understand
precedence table (I never did), you can write clever code. But which parts were difficult and needed extra illumination. In the
if you have to think about it, it will confuse the areas in which I got ambitious and included too many features all at
reader/maintainer of that code. So forget about precedence, once, I came to know – through the process of presenting the
and use parentheses when things aren’t clear. This same material – that if you include a lot of new features, you have to
attitude will be taken with some information in the C++ explain them all, and the student’s confusion is easily compounded.
language, which I think is more important for compiler As a result, I’ve taken a great deal of trouble to introduce the
writers than for programmers. features as few at a time as possible; ideally, only one major concept
at a time per chapter.
5. Keep each section focused enough so the lecture time – and
the time between exercise periods – is reasonable. Not only The goal, then, is for each chapter to teach a single concept, or a
does this keep the audience’s minds more active and involved small group of associated concepts, in such a way that no additional
during a hands-on seminar, it gives the reader a greater sense features are relied upon. That way you can digest each piece in the
of accomplishment. context of your current knowledge before moving on. To accomplish
this, I leave some C features in place for longer than I would prefer.
6. Provide readers with a solid foundation so they can The benefit is that you will not be confused by seeing all the C++
understand the issues well enough to move on to more features used before they are explained, so your introduction to the
difficult coursework and books (in particular, Volume 2 of language will be gentle and will mirror the way you will assimilate
this book). the features if left to your own devices.
6 Thinking in C++ www.BruceEckel.com Preface 7
15. Here is a brief description of the chapters contained in this book: by the simple act of putting functions inside structures, the details
of how to do it, and what kind of code it creates. You’ll also learn the
Chapter 1: Introduction to Objects. When projects became too best way to organize your code into header files and
big and complicated to easily maintain, the “software crisis” was implementation files.
born, with programmers saying, “We can’t get projects done, and if
we can, they’re too expensive!” This precipitated a number of Chapter 5: Hiding the Implementation. You can decide that
responses, which are discussed in this chapter along with the ideas some of the data and functions in your structure are unavailable to
of object-oriented programming (OOP) and how it attempts to solve the user of the new type by making them private. This means that
the software crisis. The chapter walks you through the basic you can separate the underlying implementation from the interface
concepts and features of OOP and also introduces the analysis and that the client programmer sees, and thus allow that
design process. In addition, you’ll learn about the benefits and implementation to be easily changed without affecting client code.
concerns of adopting the language and suggestions for moving into The keyword class is also introduced as a fancier way to describe a
the world of C++. new data type, and the meaning of the word “object” is demystified
(it’s a fancy variable).
Chapter 2: Making and Using Objects. This chapter explains
the process of building programs using compilers and libraries. It Chapter 6: Initialization and Cleanup. One of the most
introduces the first C++ program in the book and shows how common C errors results from uninitialized variables. The
programs are constructed and compiled. Then some of the basic constructor in C++ allows you to guarantee that variables of your
libraries of objects available in Standard C++ are introduced. By the new data type (“objects of your class”) will always be initialized
time you finish this chapter you’ll have a good grasp of what it properly. If your objects also require some sort of cleanup, you can
means to write a C++ program using off-the-shelf object libraries. guarantee that this cleanup will always happen with the C++
destructor.
Chapter 3: The C in C++. This chapter is a dense overview of the
features in C that are used in C++, as well as a number of basic Chapter 7: Function Overloading and Default Arguments.
features that are available only in C++. It also introduces the C++ is intended to help you build big, complex projects. While
“make” utility that’s common in the software development world doing this, you may bring in multiple libraries that use the same
and that is used to build all the examples in this book (the source function name, and you may also choose to use the same name with
code for the book, which is available at www.BruceEckel.com, different meanings within a single library. C++ makes this easy with
contains makefiles for each chapter). Chapter 3 assumes that you function overloading, which allows you to reuse the same function
have a solid grounding in some procedural programming language name as long as the argument lists are different. Default arguments
like Pascal, C, or even some flavors of Basic (as long as you’ve allow you to call the same function in different ways by
written plenty of code in that language, especially functions). If you automatically providing default values for some of your arguments.
find this chapter a bit too much, you should first go through the
Thinking in C seminar on the CD that’s bound with this book (and Chapter 8: Constants. This chapter covers the const and
also available at www.BruceEckel.com). volatile keywords, which have additional meaning in C++,
especially inside classes. You’ll learn what it means to apply const
Chapter 4: Data Abstraction. Most features in C++ revolve to a pointer definition. The chapter also shows how the meaning of
around the ability to create new data types. Not only does this const varies when used inside and outside of classes and how to
provide superior code organization, but it lays the groundwork for create compile-time constants inside classes.
more powerful OOP abilities. You’ll see how this idea is facilitated
8 Thinking in C++ www.BruceEckel.com Preface 9
16. Chapter 9: Inline Functions. Preprocessor macros eliminate delete elegantly solve this problem by safely creating objects on the
function call overhead, but the preprocessor also eliminates heap. You’ll also see how new and delete can be overloaded in a
valuable C++ type checking. The inline function gives you all the variety of ways so you can control how storage is allocated and
benefits of a preprocessor macro plus all of the benefits of a real released.
function call. This chapter thoroughly explores the implementation
and use of inline functions. Chapter 14: Inheritance and Composition. Data abstraction
allows you to create new types from scratch, but with composition
Chapter 10: Name Control. Creating names is a fundamental and inheritance, you can create new types from existing types. With
activity in programming, and when a project gets large, the number composition, you assemble a new type using other types as pieces,
of names can be overwhelming. C++ allows you a great deal of and with inheritance, you create a more specific version of an
control over names in terms of their creation, visibility, placement existing type. In this chapter you’ll learn the syntax, how to redefine
of storage, and linkage. This chapter shows how names are functions, and the importance of construction and destruction for
controlled in C++ using two techniques. First, the static keyword is inheritance and composition.
used to control visibility and linkage, and its special meaning with
classes is explored. A far more useful technique for controlling Chapter 15: Polymorphism and virtual Functions. On your
names at the global scope is C++’s namespace feature, which own, you might take nine months to discover and understand this
allows you to break up the global name space into distinct regions. cornerstone of OOP. Through small, simple examples, you’ll see
how to create a family of types with inheritance and manipulate
Chapter 11: References and the Copy-Constructor. C++ objects in that family through their common base class. The virtual
pointers work like C pointers with the additional benefit of stronger keyword allows you to treat all objects in this family generically,
C++ type checking. C++ also provides an additional way to handle which means that the bulk of your code doesn’t rely on specific type
addresses: from Algol and Pascal, C++ lifts the reference, which lets information. This makes your programs extensible, so building
the compiler handle the address manipulation while you use programs and code maintenance is easier and cheaper.
ordinary notation. You’ll also meet the copy-constructor, which
controls the way objects are passed into and out of functions by Chapter 16: Introduction to Templates. Inheritance and
value. Finally, the C++ pointer-to-member is illuminated. composition allow you to reuse object code, but that doesn’t solve
all of your reuse needs. Templates allow you to reuse source code by
Chapter 12: Operator Overloading. This feature is sometimes providing the compiler with a way to substitute type names in the
called “syntactic sugar;” it lets you sweeten the syntax for using body of a class or function. This supports the use of container class
your type by allowing operators as well as function calls. In this libraries, which are important tools for the rapid, robust
chapter you’ll learn that operator overloading is just a different type development of object-oriented programs (the Standard C++
of function call and you’ll learn how to write your own, dealing with Library includes a significant library of container classes). This
the sometimes-confusing uses of arguments, return types, and the chapter gives you a thorough grounding in this essential subject.
decision of whether to make an operator a member or friend.
Additional topics (and more advanced subjects) are available in
Chapter 13: Dynamic Object Creation. How many planes will Volume 2 of this book, which can be downloaded from the Web site
an air-traffic system need to manage? How many shapes will a CAD www.BruceEckel.com.
system require? In the general programming problem, you can’t
know the quantity, lifetime, or type of objects needed by your
running program. In this chapter, you’ll learn how C++’s new and
10 Thinking in C++ www.BruceEckel.com Preface 11
17. All rights reserved EXCEPT as allowed by the
Exercises following statements: You can freely use this file
I’ve discovered that exercises are exceptionally useful during a for your own work (personal or commercial),
seminar to complete a student’s understanding, so you’ll find a set including modifications and distribution in
executable form only. Permission is granted to use
at the end of each chapter. The number of exercises has been greatly
this file in classroom situations, including its
increased over the number in the first edition. use in presentation materials, as long as the book
"Thinking in C++" is cited as the source.
Many of the exercises are fairly simple so that they can be finished Except in classroom situations, you cannot copy
in a reasonable amount of time in a classroom situation or lab and distribute this code; instead, the sole
section while the instructor observes, making sure all students are distribution point is http://www.BruceEckel.com
absorbing the material. Some exercises are a bit more challenging (and official mirror sites) where it is
to keep advanced students entertained. The bulk of the exercises are available for free. You cannot remove this
copyright and notice. You cannot distribute
designed to be solved in a short time and are intended only to test
modified versions of the source code in this
and polish your knowledge rather than present major challenges package. You cannot use this file in printed
(presumably, you’ll find those on your own – or more likely, they’ll media without the express permission of the
find you). author. Bruce Eckel makes no representation about
the suitability of this software for any purpose.
It is provided "as is" without express or implied
Exercise solutions warranty of any kind, including any implied
Solutions to selected exercises can be found in the electronic warranty of merchantability, fitness for a
document The Thinking in C++ Annotated Solution Guide, particular purpose, or non-infringement. The entire
risk as to the quality and performance of the
available for a small fee from www.BruceEckel.com.
software is with you. Bruce Eckel and the
publisher shall not be liable for any damages
suffered by you or any third party as a result of
Source code using or distributing this software. In no event
will Bruce Eckel or the publisher be liable for
The source code for this book is copyrighted freeware, distributed any lost revenue, profit, or data, or for direct,
via the Web site www.BruceEckel.com. The copyright prevents you indirect, special, consequential, incidental, or
from republishing the code in print media without permission, but punitive damages, however caused and regardless of
you are granted the right to use it in many other situations (see the theory of liability, arising out of the use of
below). or inability to use software, even if Bruce Eckel
and the publisher have been advised of the
The code is available in a zipped file, designed to be extracted for possibility of such damages. Should the software
prove defective, you assume the cost of all
any platform that has a “zip” utility (most do; you can search the
necessary servicing, repair, or correction. If you
Internet to find a version for your platform if you don’t already have think you've found an error, please submit the
one installed). In the starting directory where you unpacked the correction using the form you will find at
code you will find the following copyright notice: www.BruceEckel.com. (Please use the same
form for non-code errors found in the book.)
//:! :Copyright.txt ///:~
Copyright (c) 2000, Bruce Eckel
Source code file from the book "Thinking in C++"
12 Thinking in C++ www.BruceEckel.com Preface 13
18. You may use the code in your projects and in the classroom as long Thus, ‘ISO’ is the correct way to refer to the C++ Standard.
as the copyright notice is retained.
Language support
Your compiler may not support all of the features discussed in this
Language standards book, especially if you don’t have the newest version of the
Throughout this book, when referring to conformance to the ISO C compiler. Implementing a language like C++ is a Herculean task,
standard, I will generally just say ‘C.’ Only if it is necessary to and you can expect that the features will appear in pieces rather
distinguish between Standard C and older, pre-Standard versions of than all at once. But if you attempt one of the examples in the book
C will I make a distinction. and get a lot of errors from the compiler, it’s not necessarily a bug
in the code or the compiler; it may simply not be implemented in
At this writing the C++ Standards Committee was finished working your particular compiler yet.
on the language. Thus, I will use the term Standard C++ to refer to
the standardized language. If I simply refer to C++ you should
assume I mean “Standard C++.”
The book’s CD ROM
There is some confusion over the actual name of the C++ Standards The primary content of the CD ROM packaged in the back of this
Committee and the name of the standard itself. Steve Clamage, the book is a “seminar on CD ROM” titled Thinking in C: Foundations
committee chair, clarified this: for Java & C++ by Chuck Allison (published by MindView, Inc.,
and also available in quantities at www.BruceEckel.com). This
There are two C++ standardization committees: The NCITS contains many hours of audio lectures and slides, and can be viewed
(formerly X3) J16 committee and the ISO JTC1/SC22/WG14 on most computers if you have a CD ROM player and a sound
committee. ANSI charters NCITS to create technical system.
committees for developing American national standards.
The goal of Thinking in C is to take you carefully through the
J16 was chartered in 1989 to create an American standard for fundamentals of the C language. It focuses on the knowledge
C++. In about 1991 WG14 was chartered to create an necessary for you to be able to move on to the C++ or Java
international standard. The J16 project was converted to a languages instead of trying to make you an expert in all the dark
"Type I" (International) project and subordinated to the ISO corners of C. (One of the reasons for using a higher-level language
standardization effort. like C++ or Java is precisely so we can avoid many of these dark
corners.) It also contains exercises and guided solutions. Keep in
The two committees meet at the same time at the same location, mind that because Chapter 3 of this book goes beyond the Thinking
and the J16 vote constitutes the American vote on WG14. WG14 in C CD, the CD is not a replacement for that chapter, but should be
delegates technical work to J16. WG14 votes on the technical used instead as a preparation for this book.
work of J16.
Please note that the CD ROM is browser-based, so you should have
The C++ standard was originally created as an ISO standard. a Web browser installed on your machine before using it.
ANSI later voted (as recommended by J16) to adopt the ISO
C++ standard as the American standard for C++.
14 Thinking in C++ www.BruceEckel.com Preface 15
19. CD ROMs, seminars, About the cover
and consulting The first edition of this book had my face on the cover, but I
originally wanted a cover for the second edition that was more of a
There are seminars-on-CD-ROM planned to cover Volume 1 and work of art like the Thinking in Java cover. For some reason, C++
Volume 2 of this book. These comprise many hours of audio seems to me to suggest Art Deco with its simple curves and brushed
lectures by me that accompany slides that cover selected material chrome. I had in mind something like those posters of ships and
from each chapter in the book. They can be viewed on most airplanes with the long sweeping bodies.
computers if you have a CD ROM player and a sound system. These
CDs may be purchased at www.BruceEckel.com, where you will My friend Daniel Will-Harris, (www.Will-Harris.com) whom I first
find more information and sample lectures. met in junior high school choir class, went on to become a world-
class designer and writer. He has done virtually all of my designs,
My company, MindView, Inc., provides public hands-on training including the cover for the first edition of this book. During the
seminars based on the material in this book and also on advanced cover design process, Daniel, unsatisfied with the progress we were
topics. Selected material from each chapter represents a lesson, making, kept asking “How does this relate people to computers?”
which is followed by a monitored exercise period so each student We were stuck.
receives personal attention. We also provide on-site training,
consulting, mentoring, and design and code walkthroughs. On a whim, with no particular outcome in mind, he asked me to put
Information and sign-up forms for upcoming seminars and other my face on the scanner. Daniel had one of his graphics programs
contact information can be found at www.BruceEckel.com. (Corel Xara, his favorite) “autotrace” the scan of my face. As he
describes it, “Autotracing is the computer's way to turn a picture
I am sometimes available for design consulting, project evaluation into the kinds of lines and curves it really likes.” Then he played
and code walkthroughs. When I first began writing about with it until he had something that looked like a topographic map of
computers, my primary motivation was to increase my consulting my face, an image that might be the way a computer could see
activities, because I find consulting to be challenging, educational, people.
and one of my most enjoyable experiences, professionally. Thus I
will try my best to fit you into my schedule, or to provide you with I took this image and photocopied it onto watercolor paper (some
one of my associates (who are people that I know well and trust, color copiers can handle thick stock), and then started creating lots
and often people who co-develop and teach seminars with me). of experiments by adding watercolor to the image. We selected the
ones we liked best, then Daniel scanned them back in and arranged
them into the cover, adding the text and other design elements. The
Errors whole process happened over several months, mostly because of the
No matter how many tricks a writer uses to detect errors, some time it took me to do the watercolors. But I’ve especially enjoyed it
always creep in and these often leap off the page to a fresh reader. If because I got to participate in the art on the cover, and because it
you discover anything you believe to be an error, please use the gave me incentive to do more watercolors (what they say about
correction form you will find at www.BruceEckel.com. Your help is practice really is true).
appreciated.
16 Thinking in C++ www.BruceEckel.com Preface 17
20. Book design and production Acknowledgements
The book’s interior design was created by Daniel Will-Harris, who First, thanks to everyone on the Internet who submitted corrections
used to play with rub-on letters in junior high school while he and suggestions; you’ve been tremendously helpful in improving
awaited the invention of computers and desktop publishing. the quality of this book, and I couldn’t have done it without you.
However, I produced the camera-ready pages myself, so the Special thanks to John Cook.
typesetting errors are mine. Microsoft® Word for Windows
Versions 8 and 9 were used to write the book and to create camera- The ideas and understanding in this book have come from many
ready pages, including generating the table of contents and index. (I sources: friends like Chuck Allison, Andrea Provaglio, Dan Saks,
created a COM automation server in Python, called from Word VBA Scott Meyers, Charles Petzold, and Michael Wilk; pioneers of the
macros, to aid me in index marking.) Python (see language like Bjarne Stroustrup, Andrew Koenig, and Rob Murray;
www.Python.org) was used to create some of the tools for checking members of the C++ Standards Committee like Nathan Myers (who
the code, and would have been use for the code extraction tool had I was particularly helpful and generous with his insights), Bill
discovered it earlier. Plauger, Reg Charney, Tom Penello, Tom Plum, Sam Druker, and
Uwe Steinmueller; people who have spoken in my C++ track at the
I created the diagrams using Visio® – thanks to Visio Corporation Software Development Conference; and often students in my
for creating a useful tool. seminars, who ask the questions I need to hear in order to make the
material more clear.
The body typeface is Georgia and the headlines are in Verdana. The
final camera-ready version was produced in Adobe® Acrobat 4 and A huge thank-you to my friend Gen Kiyooka, whose company
taken directly to press from that file – thanks very much to Adobe Digigami has provided me with a web server.
for creating a tool that allows e-mailing camera-ready documents,
as it enables multiple revisions to be made in a single day rather My friend Richard Hale Shaw and I have taught C++ together;
than relying on my laser printer and overnight express services. Richard’s insights and support have been very helpful (and Kim’s,
(We first tried the Acrobat process with Thinking in Java, and I was too). Thanks also to KoAnn Vikoren, Eric Faurot, Jennifer Jessup,
able to upload the final version of that book to the printer in the Tara Arrowood, Marco Pardi, Nicole Freeman, Barbara Hanscome,
U.S. from South Africa.) Regina Ridley, Alex Dunne, and the rest of the cast and crew at
MFI.
The HTML version was created by exporting the Word document to
RTF, then using RTF2HTML (see A special thanks to all my teachers and all my students (who are my
http://www.sunpack.com/RTF/) to do most of the work of the teachers as well).
HTML conversion. (Thanks to Chris Hector for making such a
useful, and especially reliable, tool.) The resulting files were cleaned And for favorite writers, my deep appreciation and sympathy for
up using a custom Python program that I hacked together, and the your efforts: John Irving, Neal Stephenson, Robertson Davies (we
WMFs were converted to GIFs using JASC® PaintShop Pro 6 and its shall miss you), Tom Robbins, William Gibson, Richard Bach,
batch conversion tool (thanks to JASC for solving so many Carlos Castaneda, and Gene Wolfe.
problems for me with their excellent product). The color syntax
highlighting was added via a Perl script kindly contributed by Zafir To Guido van Rossum, for inventing Python and giving it selflessly
Anjum. to the world. You have enriched my life with your contribution.
18 Thinking in C++ www.BruceEckel.com Preface 19