[This is the Preface from the book-length version of the C FAQ list: C Programming FAQs: Frequently Asked Questions, Addison-Wesley, 1995, ISBN 0-201-84519-9.]


At some point in 1979, I heard a lot of people talking about this relatively new language, C, and the book which had just come out about it. I bought a copy of K&R, otherwise known as The C Programming Language, by Brian Kernighan and Dennis Ritchie, but it sat on my shelf for a while because I didn't have an immediate need for it (besides which I was busy being a college freshman at the time). It proved in the end to be an auspicious purchase, though, because when I finally did take it up, I never put it down: I've been programming in C ever since.

In 1983, I came across the Usenet newsgroup net.lang.c, which was (and its successor comp.lang.c still is) an excellent place to learn a lot more about C, and to find out what questions everyone else is having about C, and to discover that you may not know all there is to know about C after all. It seems that C, despite its apparent simplicity, has a number of decidedly non-obvious aspects, and certain questions come up over and over again. This book is a collection of some of those questions, with answers, based on the Frequently-Asked Questions (``FAQ'') list which I began posting to comp.lang.c in May, 1990.

I hasten to add, however, that this book is not intended as a critique or ``hatchet job'' on the C language. It is all too easy to blame a language (or any tool) for the difficulties its users encounter with it, or to claim that a properly-designed tool ``ought'' to prevent its users from misusing it. It would therefore be easy to regard a book like this, with its long lists of misuses, as a litany of woes attempting to show that the language is hopelessly deficient. Nothing could be farther from the case.

I would never have learned enough about C to be able to write this book, and I would not be attempting to make C more pleasant for others to use by writing this book now, if I did not think that C was a great language or if I did not enjoy programming in it. I do like C, and one of the reasons that I teach classes in it and spend time participating in discussion about it on the Internet is that I would like to discover which aspects of C (or of programming in general) are difficult to learn or keep people from being able to program efficiently and effectively. This book represents some of what I've learned: these questions are certainly some of the ones people have the most trouble with, and the answers have been refined over a several-year period in an attempt to ensure that people don't have too much trouble with them.

A reader will certainly have trouble if there are any errors in these answers, and although the reviewers and I have worked hard to eliminate them, it can be as hard to eradicate the last error from a large manuscript as it is to stamp out the last bug in a program. I will appreciate any corrections or suggestions sent to me in care of the publisher or at the e-mail address below, and I would like to offer the customary $1.00 reward to the first finder of any error. If you have access to the Internet, you can check for an errata list (and a scorecard of the finders) at the ftp and http addresses mentioned in question 20.40.

As I hope I've made clear, this book is not a critique of the C Programming language, nor is it a critique of the book from which I first learned C, nor of that book's authors. I didn't just learn C from K&R; I also learned a lot about programming. As I contemplate my own contribution to the C programming literature, my only regret is that the present book does not live up to a nice observation made in the second edition of K&R, namely that ``C is not a big language, and it is not well served by a big book.'' I hope that those who most deeply appreciate C's brevity and precision (and that of K&R) will not be too offended by the fact that this book says some things over and over and over, or in three slightly different ways.

Though my name is on the cover, there are a lot of people behind this book, and it's hard to know where to start handing out acknowledgments. In a sense, every one of comp.lang.c's readers (today estimated at 320,000) is a contributor: the FAQ list behind this book was written for comp.lang.c first, and this book retains the flavor of a good comp.lang.c discussion.

This book also retains, I hope, the philosophy of correct C programming which I began learning when I started reading net.lang.c. Therefore, I shall first acknowledge the posters who stand out in my mind as having most clearly and consistently articulated that philosophy: Doug Gwyn, Guy Harris, Karl Heuer, Henry Spencer, and Chris Torek. These gentlemen have displayed remarkable patience over the years, answering endless questions with generosity and wisdom. I was the one who stuck his neck out and started writing the Frequent questions down, but I would hate to give the impression that the answers are somehow mine. I was once the student (I believe it was Guy who answered my post asking essentially the present volume's question 5.10), and I owe a real debt to the masters who went before me. This book is theirs as much as mine, though I retain title to any inadequacies or mistakes I've made in the presentation.

The former on-line FAQ list grew by a factor of three in the process of becoming this book, and its growth was a bit rapid and awkward at times. Mark Brader, Vinit Carpenter, Stephen Clamage, Jutta Degener, Doug Gwyn, Karl Heuer, Joseph Kent, and George Leach read proposals or complete drafts and helped to exert some control over the process; I thank them for their many careful suggestions and corrections. Their efforts grew out of a shared wish to improve the overall understanding of C in the programming community. I appreciate their dedication.

Three of those reviewers have also been long-time contributors to the on-line FAQ list. I thank Jutta Degener and Karl Heuer for their help over the years, and I especially thank Mark Brader, who has been my most persistent critic ever since I first began posting the comp.lang.c FAQ list five years ago. I don't know how he has had the stamina to make as many suggestions and corrections as he has, and to overcome my continuing stubborn refusal to agree with some of them, even though (as I eventually understood) they really were improvements. You can thank Mark for the form of many of this book's explanations, and blame me for mangling any of them.

Additional assorted thanks: to Susan Cyr for the cover art; to Bob Dinse and Eskimo North for providing the network access which is particularly vital to a project like this; to Bob Holland for providing the computer on which I've done most of the writing; to Pete Keleher for the Alpha text editor; to the University of Washington Mathematics Research and Engineering libraries for access to their collections; and to the University of Washington Oceanography department for letting me borrow their tape drives to access my dusty old archives of Usenet postings.

Thanks to Tanmoy Bhattacharya for the example in question 11.10, to Arjan Kenter for the code in question 13.7, to Tomohiko Sakamoto for the code in question 20.31, and to Roger Miller for the line in question 11.35.

Finally, I'd like to thank my editor at Addison-Wesley, Debbie Lafferty, for tapping me on the electronic shoulder one day and asking if I might be interested in writing this book. I was, and you now hold it, and I hope that it may help to make C programming as pleasant for you as it is for me.

Steve Summit

Seattle, Washington
July, 1995