Archive-name: C-faq/faq
Comp-lang-c-archive-name: C-FAQ-list
URL: http://www.eskimo.com/~scs/C-faq/top.html

[Last modified February 7, 1999 by scs.]

This article is Copyright 1990-1999 by Steve Summit.  Content from the
book _C Programming FAQs: Frequently Asked Questions_ is made available
here by permission of the author and the publisher as a service to the
community.  It is intended to complement the use of the published text
and is protected by international copyright laws.  The content is made
available here and may be accessed freely for personal use but may not
be republished without permission.

Certain topics come up again and again on this newsgroup.  They are good
questions, and the answers may not be immediately obvious, but each time
they recur, much net bandwidth and reader time is wasted on repetitive
responses, and on tedious corrections to the incorrect answers which are
inevitably posted.

This article, which is posted monthly, attempts to answer these common
questions definitively and succinctly, so that net discussion can move
on to more constructive topics without continual regression to first
principles.

No mere newsgroup article can substitute for thoughtful perusal of a
full-length tutorial or language reference manual.  Anyone interested
enough in C to be following this newsgroup should also be interested
enough to read and study one or more such manuals, preferably several
times.  Some C books and compiler manuals are unfortunately inadequate;
a few even perpetuate some of the myths which this article attempts to
refute.  Several noteworthy books on C are listed in this article's
bibliography; see also questions 18.9 and 18.10.  Many of the questions
and answers are cross-referenced to these books, for further study by
the interested and dedicated reader.

If you have a question about C which is not answered in this article,
first try to answer it by checking a few of the referenced books, or by
asking knowledgeable colleagues, before posing your question to the net
at large.  There are many people on the net who are happy to answer
questions, but the volume of repetitive answers posted to one question,
as well as the growing number of questions as the net attracts more
readers, can become oppressive.  If you have questions or comments
prompted by this article, please reply by mail rather than following up --
this article is meant to decrease net traffic, not increase it.

Besides listing frequently-asked questions, this article also summarizes
frequently-posted answers.  Even if you know all the answers, it's worth
skimming through this list once in a while, so that when you see one of
its questions unwittingly posted, you won't have to waste time
answering.  (However, this is a large and heavy document, so don't
assume that everyone on the newsgroup has managed to read all of it in
detail, and please don't roll it up and thwack people over the head with
it just because they missed their answer in it.)

This article was last modified on February 7, 1999, and its travels may
have taken it far from its original home on Usenet.  It may, however,
be out-of-date, particularly if you are looking at a printed copy
or one retrieved from a tertiary archive site or CD-ROM.  You should
be able to obtain the most up-to-date copy on the web at
http://www.eskimo.com/~scs/C-faq/top.html or http://www.faqs.org/faqs/ ,
or from one of the ftp sites mentioned in question 20.40.  Since this
list is modified from time to time, its question numbers may not match
those in older or newer copies which are in circulation; be careful when
referring to FAQ list entries by number alone.

This article was produced for free redistribution.  You should not need
to pay anyone for a copy of it.

Other versions of this document are also available.  Posted along with
it are an abridged version and (when there are changes) a list of
differences with respect to the previous version.  A hypertext version
is available on the web at the aforementioned URL.  Finally, for those
who might prefer a bound, hardcopy version (and even longer answers to
even more questions!), a book-length version has been published by
Addison-Wesley (ISBN 0-201-84519-9).

This article is always being improved.  Your input is welcomed.  Send
your comments to scs@eskimo.com .

The questions answered here are divided into several categories:

	 1. Declarations and Initializations
	 2. Structures, Unions, and Enumerations
	 3. Expressions
	 4. Pointers
	 5. Null Pointers
	 6. Arrays and Pointers
	 7. Memory Allocation
	 8. Characters and Strings
	 9. Boolean Expressions and Variables
	10. C Preprocessor
	11. ANSI/ISO Standard C
	12. Stdio
	13. Library Functions
	14. Floating Point
	15. Variable-Length Argument Lists
	16. Strange Problems
	17. Style
	18. Tools and Resources
	19. System Dependencies
	20. Miscellaneous
	    Bibliography
	    Acknowledgements

(The question numbers within each section are not always continuous,
because they are aligned with the aforementioned book-length version,
which contains even more questions.)

Herewith, some frequently-asked questions and their answers: