www.it-ebooks.info www.it-ebooks.info C IN A NUTSHELL www.it-ebooks.info Other resources from O’Reilly Related titles C Pocket Reference Practical C Programming Secure Programming Cookbook for C and C++ Programming Embedded Systems with C and C++ Programming with GNU Software Objective-C Pocket Reference Prefactoring Practical Development Environments oreilly.com oreilly.com is more than a complete catalog of O’Reilly books. You’ll also find links to news, events, articles, web- logs, sample chapters, and code examples. oreillynet.com is the essential portal for developers inter- ested in open and emerging technologies, including new platforms, programming languages, and operating systems. Conferences O’Reilly brings diverse innovators together to nurture the ideas that spark revolutionary industries. We specialize in documenting the latest tools and systems, translating the innovator’s knowledge into useful skills for those in the trenches. Visit conferences.oreilly.com for our upcoming events. Safari Bookshelf (safari.oreilly.com) is the premier online reference library for programmers and IT professionals. Conduct searches across more than 1,000 books. Sub- scribers can zero in on answers to time-critical questions in a matter of seconds. Read the books on your Book- shelf from cover to cover or simply flip to the page you need. Try it today for free. www.it-ebooks.info C IN A NUTSHELL Peter Prinz and Tony Crawford Beijing • Cambridge • Farnham • Köln • Sebastopol • Tokyo www.it-ebooks.info C in a Nutshell by Peter Prinz and Tony Crawford Copyright © 2006 O’Reilly Media, Inc. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (safari.oreilly.com). For more information, contact our corporate/institutional sales department: (800) 998-9938 or corporate@oreilly.com. Editor: Jonathan Gennick Production Editor: A. J. Fox Cover Designer: Karen Montgomery Interior Designer: David Futato Printing History: December 2005: First Edition. Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are registered trademarks of O’Reilly Media, Inc. The In a Nutshell series designations, C in a Nutshell, the image of a cow, and related trade dress are trademarks of O’Reilly Media, Inc. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and O’Reilly Media, Inc. was aware of a trademark claim, the designations have been printed in caps or initial caps. While every precaution has been taken in the preparation of this book, the publisher and authors assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. ISBN: 978-0-596-00697-6 [LSI] [2012-05-11] www.it-ebooks.info v This is the Title of the Book, eMatter Edition Copyright © 2012 O’Reilly & Associates, Inc. All rights reserved. Chapter 1 Table of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Part I. Language 1. Language Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Characteristics of C 3 The Structure of C Programs 4 Source Files 6 Comments 7 Character Sets 8 Identifiers 13 How the C Compiler Works 16 2. Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Typology 20 Integer Types 21 Floating-Point Types 26 Complex Floating-Point Types (C99) 28 Enumerated Types 29 The Type void 30 3. Literals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Integer Constants 32 Floating-Point Constants 33 www.it-ebooks.info vi | Table of Contents This is the Title of the Book, eMatter Edition Copyright © 2012 O’Reilly & Associates, Inc. All rights reserved. Character Constants 34 String Literals 37 4. Type Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Conversion of Arithmetic Types 41 Conversion of Nonarithmetic Types 48 5. Expressions and Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 How Expressions Are Evaluated 56 Operators in Detail 59 Constant Expressions 81 6. Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Expression Statements 83 Block Statements 84 Loops 85 Selection Statements 89 Unconditional Jumps 92 7. Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Function Definitions 96 Function Declarations 103 How Functions Are Executed 104 Pointers as Arguments and Return Values 104 Inline Functions 106 Recursive Functions 107 Variable Numbers of Arguments 108 8. Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Defining Arrays 111 Accessing Array Elements 113 Initializing Arrays 114 Strings 116 Multidimensional Arrays 117 Arrays as Arguments of Functions 120 9. Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Declaring Pointers 122 Operations with Pointers 125 Pointers and Type Qualifiers 129 Pointers to Arrays and Arrays of Pointers 132 Pointers to Functions 136 www.it-ebooks.info Table of Contents | vii This is the Title of the Book, eMatter Edition Copyright © 2012 O’Reilly & Associates, Inc. All rights reserved. 10. Structures, Unions, and Bit-Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Structures 139 Unions 149 Bit-Fields 151 11. Declarations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 General Syntax 153 Type Names 160 typedef Declarations 161 Linkage of Identifiers 163 Storage Duration of Objects 164 Initialization 165 12. Dynamic Memory Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 Allocating Memory Dynamically 168 Characteristics of Allocated Memory 169 Resizing and Releasing Memory 170 An All-Purpose Binary Tree 171 Characteristics 172 Implementation 172 13. Input and Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 Streams 182 Files 183 Opening and Closing Files 186 Reading and Writing 188 Random File Access 205 14. Preprocessing Directives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Inserting the Contents of Header Files 210 Defining and Using Macros 211 Conditional Compiling 218 Defining Line Numbers 220 Generating Error Messages 221 The #pragma Directive 221 The _Pragma Operator 222 Predefined Macros 223 www.it-ebooks.info viii | Table of Contents This is the Title of the Book, eMatter Edition Copyright © 2012 O’Reilly & Associates, Inc. All rights reserved. Part II. Standard Library 15. The Standard Headers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 Using the Standard Headers 227 Contents of the Standard Headers 230 16. Functions at a Glance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 Input and Output 252 Mathematical Functions 253 Character Classification and Conversion 260 String Processing 262 Multibyte Characters 263 Converting Between Numbers and Strings 264 Searching and Sorting 264 Memory Block Handling 265 Dynamic Memory Management 265 Date and Time 266 Process Control 267 Internationalization 268 Nonlocal Jumps 269 Debugging 269 Error Messages 270 17. Standard Library Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 Part III. Basic Tools 18. Compiling with GCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491 The GNU Compiler Collection 491 Obtaining and Installing GCC 492 Compiling C Programs with GCC 493 C Dialects 501 Compiler Warnings 502 Optimization 503 Debugging 507 Profiling 507 Option and Environment Variable Summary 508 www.it-ebooks.info [...]... for a lowercase alpha In multibyte character sets, each character is coded as a sequence of one or more bytes Both the source and execution character sets may contain multibyte characters If they do, then each character in the basic character set occupies only one byte, and no multibyte character except the null character may contain any byte in which all bits are 0 Multibyte characters can be used in. .. horizontal tab, vertical tab, new line, and form feed The basic execution character set also includes four nonprintable characters: the null character, which acts as the termination mark in a character string; alert; backspace; and carriage return To represent these characters in character and 8 | Chapter 1: Language Basics This is the Title of the Book, eMatter Edition www.it-ebooks.info Copyright... divided into two source files Example 1-2 The first source file, containing the main( ) function // circle .c: Prints the areas of circles // Uses circulararea .c for the math #include double circularArea( double r ); int main( ) { /* As in Example 1-1 */ } Example 1-3 The second source file, containing the circularArea( ) function // circulararea .c: Calculates the areas of circles // Called... executed, the execution environment Accordingly, C defines two character sets: the source character set is the set of characters that may be used in C source code, and the execution character set is the set of characters that can be interpreted by the running program In many C implementations, the two character sets are identical If they are not, then the compiler converts the characters in character... O’Reilly & Associates, Inc All rights reserved | 9 Language Basics string literals, type the corresponding escape sequences beginning with a backslash: \0 for the null character, \a for alert, \b for backspace, and \r for carriage return See Chapter 3 for more details The escape sequence beginning with \x indicates a character code in hexadecimal notation to be stored in the variable in this case, the code... character constants and string literals in the source code into the corresponding elements of the execution character set Each of the two character sets includes both a basic character set and extended characters The C language does not specify the extended characters, which are usually dependent on the local language The extended characters together with the basic character set make up the extended character... character constants and string literals are converted into the corresponding characters in the execution character set 6 Adjacent string literals are concatenated into a single string 7 The actual compiling takes place: the compiler analyzes the sequence of tokens and generates the corresponding machine code 8 The linker resolves references to external objects and functions, and generates the executable... character set is UTF-16, then you need to define the variable as a wide character: wchar_t alpha = '\u03B1'; In this case, the character code value assigned to alpha is hexadecimal 3B1, the same as the universal character name Not all compilers support universal character names Digraphs and Trigraphs C provides alternative representations for a number of punctuation marks that are not available on all... & Associates, Inc All rights reserved The actual numeric values of characters—the character codes—may vary from one C implementation to another The language itself imposes only the following conditions: • Each character in the basic character set must be representable in one byte • The null character is a byte in which all bits are 0 • The value of each decimal digit after 0 is greater by one than... internationally, a variety of multibyte character encoding schemes have been in use for decades to represent non-Latin alphabets and the nonalphabetic Chinese, Japanese, and Korean writing systems In 1994, with the adoption of “Normative Addendum 1,” ISO C standardized two ways of representing larger character sets: wide characters, in which the same bit width is used for every character in a character . function calls, including recursive and inline functions. Chapter 8, Arrays Describes fixed-length and variable-length arrays, including strings, array initialization,. pointers and arrays are not described in full detail until Chapters 8 and 9. Chapter 1, Language Basics Describes the characteristics of the language and