Add Book to My BookshelfPurchase This Book Online

Appendix A - Significant Changes in ANSI C

UNIX Systems Programming for SVR4
David A. Curry
 Copyright © 1996 O'Reilly & Associates, Inc.

Appendix A: Significant Changes in ANSI C
Overview
From its inception, the C programming language was defined by the book The C Programming Language by Brian Kernighan and Dennis Ritchie. Unfortunately, while the book was an excellent tool for learning the language, it was not an unambiguous specification of the language. This resulted in a variety of compilers which, while mostly compatible, would do different things with certain constructs, creating a portability nightmare. Furthermore, a few extensions were added to the language at various points (enumerated types, the void type, and structures as function arguments and return values) but never sufficiently documented, resulting in different levels of support in different compilers.
In the late 1980s, the American National Standards Institute set out to remedy this situation. The X3J11 Technical Committee was charged with developing a standard for the C programming language that clarified the ambiguities in the language, and solved the problems of divergent implementations. For the most part, the committee attempted to codify existing practice, rather than invent new language mechanisms. However, where it seemed valuable, the committee did define some new features that were thought to be generally useful. Overall, they did a pretty good job (although there are some surprising lapses).
In 1989, ANSI Standard X3.159 was released, and became the standard for the C programming language. Most modern C compilers implement the ANSI version of the language, including the compilers described in Chapter 1, Introduction to SVR4. In this appendix, we describe some of the more significant changes made in ANSI C. This is not an exhaustive list; if you need more information, you should consult the standard itself, or one of the numerous books on the topic (Kernighan and Ritchie, Second Edition, is the definitive reference). If you are already a proficient C programmer, you may wish to examine A C User's Guide to ANSI C, by Ken Arnold and John Peyton, published by Addison-Wesley. This book presents all the changes in a concise manner for readers who already know the pre-ANSI version of the language.

Previous SectionNext Section
Books24x7.com, Inc © 2000 –  Feedback