Introduction C C CC Advanced C i
ii Advanced C
C CIntroduction CC C CC Advanced C Peter D. Hipson A Division of Prentice Hall Computer Publishing 201 W. 103rd St., Indianapolis, Indiana 46290 USA iii
Advanced C 1992 by Sams Publishing All rights reserved. Printed in the United States of America. No part of this book may be used or reproduced in any form or by any means, or stored in a database or retrieval system, without prior written permission of the publisher except in the case of brief quotations embodied in critical articles and reviews. Making copies of any part of this book for any purpose other than your own personal use is a violation of United States copyright laws. For information, address Sams Publishing, 201 W. 103rd St., Indianapolis, IN 46290 International Standard Book Number: 0-672-30168-7 Library of Congress Catalog Card Number: 92-061304 96 95 94 93 92 8 7 6 5 4 3 Interpretation of the printing code: the rightmost double-digit number is the year of the book s printing; the rightmost single-digit number, the number of the book s printing. For example, a printing code of 92-1 shows that the first printing of the book occurred in 1992. Composed in AGaramond and MCPdigital by Prentice Hall Computer Publishing. Screen reproductions in this book were created by means of the program Collage Plus, from Inner Media, Inc., Hollis, NH. Trademarks All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Sams Publishing cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. iv
Introduction C C CC Publisher Richard K. Swadley Production Analyst Mary Beth Wakefield Acquisitions Manager Jordan Gold Book Design Michele Laseau Managing Editor Neweleen A. Trebnik Cover Art Tim Amrhein Acquisitions Editor Production Editor Technical Reviewer Editorial Assistants Formatter Production Director Production Manager Stacy Hiquet Mary Corder Timothy C. Moore Rosemarie Graham Lori Kelley Pat Whitmer Jeff Valler Corinne Walls Graphic Images Specialist Production Index Dennis Sheehan Katy Bodenmiller Christine Cook Lisa Daugherty Denny Hager Carla Hall-Batton John Kane Roger Morgan Juli Pavey Angela Pozdol Linda Quigley Michele Self Susan Shepard Greg Simsic Alyssa Yesh Hilary Adams Imprint Manager Matthew Morrill Proofreading/Indexing Coordinator Joelynn Gifford v
Advanced C About the Author Peter Hipson and his wife live and work in New Hampshire. He has worked with computers since 1972, in hardware design and software development. He has developed numerous software programs for both PCs and larger systems. He holds patents in the field of CPU design and has been involved with microcomputers since their inception. Peter is the developer of the Windows applications STARmanager and STARmanager A/E. You can contact Peter Hipson at P.O. Box 88, West Peterborough, NH, 03468. Enclosing an SASE greatly enhances the likelihood of a reply. To Bianca, who has shown me what great fun it is having a granddaughter. vi
Introduction C C CC Overview Introduction...xxiii Part I Honing Your C Skills 1 1 The C Philosophy... 3 2 Data Types, Constants, Variables, and Arrays... 19 3 Pointers and Indirection... 65 4 Special Pointers and Their Usage... 99 5 Decimal, Binary, Hex, and Octal... 139 6 Separate Compilation and Linking... 161 Part II Managing Data in C 189 7 C Structures... 191 8 Dynamic Memory Allocation... 227 9 Disk Files and Other I/O... 249 10 Data Management: Sorts, Lists, and Indexes... 321 Part III Working with Others 433 11 C and Other Langauages... 435 12 C and Databases... 467 13 All About Header Files... 497 vii
Advanced C Part IV Documenting the Differences 519 14 ANSI C s Library Functions... 521 15 Preprocessor Directives... 621 16 Debugging and Efficiency... 641 Part V Appendixes 677 A The ASCII Character Set... 679 B Compiler Variations... 681 C Introduction to C++... 695 D Function/Header File Cross Reference... 723 Index... 741 viii
Introduction C C CC Contents Introduction...xxiii Part I: Honing Your C Skills... 1 1 The C Philosophy... 3 A Brief History of C and the Standard...3 A Programming Style...11 Memory Models...17 Summary...18 2 Data Types, Constants, Variables, and Arrays... 19 Data Types...19 Constants...25 Definitions versus Declarations...29 Declarations...30 Definitions...33 Variables...35 Variable Types and Initializing Variables...35 Scope (Or I Can See You)...37 Life Span (Or How Long Is It Going To Be Here?)...39 Type Casting...41 Arrays...46 Declaration of Arrays...46 Definition of an Array...47 Array Indexing...48 Using Array Names as Pointers...55 Strings: Character Arrays...56 Using Arrays of Pointers...58 Summary...62 ix
Advanced C 3 Pointers and Indirection... 65 Pointers, Indirection, and Arrays...65 Pointers...66 Indirection...69 An Example of Pointers, Indirection, and Arrays...69 Character Arrays and Strings...74 Indirection to Access Character Strings...79 Protecting Strings in Memory...90 Ragged-Right String Arrays...92 Summary...98 4 Special Pointers and Their Use... 99 Command Line Arguments...99 Function Pointers...114 Menus and Pointers...120 State Machines...135 Summary...137 5 Decimal, Binary, Hex, and Octal... 139 Decimal...139 Binary...141 Hex...142 Octal...144 Looking at a File...146 Bit Operators...154 Bit Fields...155 Summary...158 6 Separate Compilation and Linking... 161 Compiling and Linking Multiple Source Files...162 Compiling Multifile Programs...164 Linking Multifile Programs...164 Using #include...166 External Variables...171 Using an Object Library Manager...181 Using MAKE Files...182 Summary...186 x
Table Introduction of Contents Part II: Managing Data in C 189 C C CC 7 C Structures... 191 Using the struct Keyword...191 Arrays of Structures...195 Structures of Arrays...200 Structures of Structures...203 Bit Fields in Structures...206 Using the typedef Keyword...208 Using the offsetof() Macro...213 Pointers to Structures...216 Understanding unions...219 Summary...226 8 Dynamic Memory Allocation... 227 Using the malloc( ) Function...228 Using the calloc( ) Function...232 Using the free( ) Function...235 Using the realloc( ) Function...237 Allocating Arrays...244 Global Memory versus Local Memory...247 Summary...248 9 Disk Files and Other I/O... 249 File I/O Basics...250 Text Files and Binary Files...251 Creating and Using Temporary Work Files...256 Stream Files and Default File Handles...268 The stdin File...271 The stdout File...272 The stderr File...272 The stdaux File...273 The stdprn File...274 Low-Level I/O and File Handles...278 Standard Low-Level File Handles...280 Console and Port I/O...280 Direct Port I/O...288 xi
Advanced C The PC Printer Ports...289 The PC Communications Ports...296 Summary...318 10 Data Management: Sorts, Lists, and Indexes... 321 Sorting...322 Merging...329 Purging...336 Sorting, Merging, and Purging All in One...343 Linked Lists...344 Using Dynamic Memory...345 Disk-Based Lists...346 Double Linked Lists...346 Indexing...367 Fixed-field Disk Files...392 B-trees...392 Summary...430 Part III: Working with Others... 433 11 C and Other Languages... 435 Other Languages...436 Assembly...438 FORTRAN...441 Pascal...442 BASIC...443 Calling Other Languages from C...443 Calling Assembly from C...447 Calling FORTRAN and Pascal from C...449 Calling C Functions from Other Languages...450 Calling C from Assembly...451 Calling C from FORTRAN and Pascal...462 All the Things that Can Go Wrong...462 Looking at Data...463 Names and Limits...465 Summary...465 xii
Table Introduction of Contents C C CC 12 C and Databases... 467 Interfacing with dbase-compatible Programs...468 Using dbase Files Directly...468 Reading dbase and dbase-compatible Files...474 Creating dbase and dbase-compatible Files...484 Updating dbase and dbase-compatible Files...494 Summary...494 13 All About Header Files... 497 Function Prototypes...497 The ANSI C Header Files...500 The assert.h File (ANSI)...501 The ctype.h File (ANSI)...502 The errno.h File (ANSI)...504 The float.h File (ANSI)...506 The io.h File...508 The limits.h File (ANSI)...508 The locale.h File (ANSI)...509 The malloc.h File...510 The math.h File (ANSI)...510 The memory.h File...511 The search.h File...511 The setjmp.h File (ANSI)...512 The signal.h File (ANSI)...512 The stdarg.h File (ANSI)...513 The stddef.h File (ANSI)...515 The stdio.h File (ANSI)...515 The stdlib.h File (ANSI)...516 String Conversion...516 Memory Allocation...516 Random Numbers...516 Communications with the Operating System...516 Search Functions...517 Integer Math...517 Multibyte Characters...517 The string.h File (ANSI)...517 The time.h File (ANSI)...518 The varargs.h File...518 Summary...518 xiii
Advanced C Part IV: Documenting the Differences 519 14 ANSI C s Library Functions... 521 Functions...522 abort()...522 abs()...522 acos()...523 asctime()...523 asin()...524 assert()...524 atan()...524 atan2()...525 atexit()...525 atof()...526 atoi()...526 atol()...526 bsearch()...527 calloc()...528 ceil()...528 clearerr()...528 clock()...529 cos()...529 cosh()...530 ctime()...530 difftime()...531 div()...531 exit()...532 exp()...532 fabs()...533 fclose()...533 feof()...533 ferror()...534 fflush()...534 fgetc()...535 fgetpos()...535 fgets()...536 floor()...536 xiv
Table Introduction of Contents C C CC fmod()...537 fopen()...537 fprintf()...538 fputc()...538 fputs()...539 fread()...539 free()...540 freopen()...540 frexp()...541 fscanf()...542 fseek()...542 fsetpos()...543 ftell()...544 fwrite()...544 getc()...545 getchar()...545 gets()...546 gmtime()...546 isalnum()...547 isalpha()...547 iscntrl()...547 isdigit()...548 isgraph()...548 islower()...549 isprint()...549 ispunct()...549 isspace()...550 isupper()...551 isxdigit()...551 labs()...551 ldexp()...552 ldiv()...552 localeconv()...553 localtime()...553 log()...554 log10()...554 longjmp()...554 malloc()...556 xv
Advanced C mblen()...556 mbstowcs()...557 mbtowc()...557 memchr()...558 memcmp()...558 memcpy()...559 memmove()...560 memset()...561 mktime()...561 modf()...562 offsetof()...562 perror()...563 pow()...564 printf()...564 putc()...564 putchar()...565 puts()...565 qsort()...566 raise()...566 rand()...567 realloc()...567 remove()...568 rename()...568 rewind()...568 scanf()...569 setbuf()...569 setjmp()...570 setlocale()...571 setvbuf()...572 signal()...573 sin()...574 sinh()...575 sprintf()...575 sqrt()...576 srand()...576 sscanf()...576 strcat()...577 strchr()...577 xvi
Table Introduction of Contents C C CC strcmp()...578 strcoll( )...579 strcpy( )...580 strcspn( )...580 strerror( )...581 strftime( )...581 strlen()...583 strncat()...584 strncmp()...584 strncpy()...585 strpbrk()...586 strrchr()...586 strspn()...587 strstr()...588 strtod()...588 strtok()...589 strtol()...590 strtoul()...591 strxfrm()...592 system()...593 tan()...594 tanh()...594 time()...595 tmpfile()...596 tmpnam()...596 tolower()...597 toupper()...597 ungetc()...597 va_arg()...598 va_end()...600 va_start()...601 vfprintf()...601 vprintf()...602 vsprintf()...604 wcstombs()...605 wctomb()...606 printf() Format Codes...606 c...607 xvii
Advanced C e and E...608 f...609 g and G...610 n...610 o...610 p and P...611 s...612 u...612 x and X...613 scanf() format codes...614 c...615 d...615 o...615 x...616 i...616 u...617 e, f, and g...617 n...618 p...618 s...618 [...]...619 Summary...619 15 Preprocessor Directives... 621 The Macro Continuation Operator (\)...622 The Stringize Operator (#)...622 The Characterize Operator (#@)...623 The Token Paste Operator (##)...624 The Defined Identifier Operator (defined())...624 The #define Directive...625 The #error Directive...628 The #include Directive...629 The #if Directive...629 The #ifdef Directive...630 The #ifndef Directive...631 The #else Directive...632 The #elif Directive...633 The #endif Directive...633 xviii
Table Introduction of Contents C C CC The #line Directive...634 The #pragma Directive...635 The message Pragma...635 The pack Pragma...636 The #undef Directive...637 Predefined Macros...637 The DATE Macro...637 The TIME Macro...637 The FILE Macro...638 The LINE Macro...638 The STDC Macro...638 NULL...638 The offsetof() Macro...638 Summary...639 16 Debugging and Efficiency... 641 Debugging...641 Common Bugs...642 Rules for Debugging...649 Using the assert() Macro...650 Debug Strings and Messages...652 Debuggers...655 Efficiency...657 32-Bit Programs...658 Compiler Optimization...660 Direct Video I/O...667 Floating-Point Optimization...667 Inline Assembly...669 Linking for Performance...670 Pascal and cdecl Calling Conventions...671 Precompiled Headers...671 Using 80286/80386/80486 Instruction Sets...671 Using a Source Profiler...672 Using Intrinsic Functions...672 Using Memory Models...673 Summary...675 xix
Advanced C Part V: Appendixes 677 A The ASCII Character Set... 679 B Compiler Variations... 681 Borland s C++ 3.1...682 Microsoft...686 C/C++ 7.0...686 QuickC for Windows 1.0...690 Watcom C/386 9.01...692 C Introduction to C++... 695 Object-Oriented Programming (OOP)...696 Abstraction...696 Encapsulation...696 Hierarchies...697 Learning C++...697 Overloading Functions...701 Declaring Variables When Needed...704 Default Function Argument Values...706 References...710 References as Return Values...711 Classes...714 D Function /Header File Cross Reference... 723 Index... 741 xx