Sams Teach Yourself C in 24 Hours (74 page)

DataRead(fptr);

}

33 067231861x AppxB 4.10.2000 11:05 AM Page 497

Answers to Quiz Questions and Exercises

497

/* function definition */

long PtrTell(FILE *fptr)

{

long reval;

reval = ftell(fptr);

printf(“The fptr is at %ld\n”, reval);

return reval;

}

/* function definition */

void DataRead(FILE *fptr)

{

char buff[MAX_LEN];

fgets(buff, MAX_LEN, fptr);

printf(“%s”, buff);

}

/* function definition */

int ErrorMsg(char *str)

{

printf(“Cannot open %s.\n”, str);

B

return FAIL;

}

3. On my machine, the data.bin binary file is 10 bytes. The following is one possible solution:

/* 22A03.c */

#include

enum {SUCCESS, FAIL};

void DataWrite(FILE *fout);

void DataRead(FILE *fin);

int ErrorMsg(char *str);

main(void)

{

FILE *fptr;

char filename[]= “data.bin”;

int reval = SUCCESS;

if ((fptr = fopen(filename, “wb+”)) == NULL){

reval = ErrorMsg(filename);

} else {

DataWrite(fptr);

rewind(fptr);

DataRead(fptr);

33 067231861x AppxB 4.10.2000 11:05 AM Page 498

498

Appendix B

fclose(fptr);

}

return reval;

}

/* function definition */

void DataWrite(FILE *fout)

{

double dnum;

int inum;

dnum = 123.45;

inum = 10000;

printf(“%5.2f\n”, dnum);

fwrite(&dnum, sizeof(double), 1, fout);

printf(“%d\n”, inum);

fwrite(&inum, sizeof(int), 1, fout);

}

/* function definition */

void DataRead(FILE *fin)

{

double x;

int y;

printf(“\nRead back from the binary file:\n”);

fread(&x, sizeof(double), (size_t)1, fin);

printf(“%5.2f\n”, x);

fread(&y, sizeof(int), (size_t)1, fin);

printf(“%d\n”, y);

}

/* function definition */

int ErrorMsg(char *str)

{

printf(“Cannot open %s.\n”, str);

return FAIL;

}

4. The following is one possible solution:

/* 22A04.c */

#include

enum {SUCCESS, FAIL,

MAX_NUM = 3,

STR_LEN = 23};

void DataRead(FILE *fin);

int ErrorMsg(char *str);

33 067231861x AppxB 4.10.2000 11:05 AM Page 499

Answers to Quiz Questions and Exercises

499

main(void)

{

FILE *fptr;

char filename[]= “strnum.mix”;

int reval = SUCCESS;

if ((fptr = freopen(filename, “r”, stdin)) == NULL){

reval = ErrorMsg(filename);

} else {

DataRead(fptr);

fclose(fptr);

}

return reval;

}

/* function definition */

void DataRead(FILE *fin)

{

int i;

int miles;

char cities[STR_LEN];

printf(“The data read:\n”);

B

for (i=0; i

scanf(“%s%d”, cities, &miles);

printf(“%-23s %d\n”, cities, miles);

}

}

/* function definition */

int ErrorMsg(char *str)

{

printf(“Cannot open %s.\n”, str);

return FAIL;

}

Hour 23, “Compiling Programs: The C

Preprocessor”

Quiz

1. The semicolon (;) should not be included at the end of the macro definition because a macro definition ends with a newline, not a semicolon.

2. The value of 82 is assigned to result due to the assignment expression result =

1 + 9 * 9.

33 067231861x AppxB 4.10.2000 11:05 AM Page 500

500

Appendix B

3. The message of Under #else. is printed out.

4. The message of Under #ifdef. is printed out.

Exercises

1. The following is one possible solution:

/* 23A01.c */

#include

/* main() function */

main()

{

#define human 100

#define animal 50

#define computer 51

#define SUN 0

#define MON 1

#define TUE 2

#define WED 3

#define THU 4

#define FRI 5

#define SAT 6

printf(“human: %d, animal: %d, computer: %d\n”,

human, animal, computer);

printf(“SUN: %d\n”, SUN);

printf(“MON: %d\n”, MON);

printf(“TUE: %d\n”, TUE);

printf(“WED: %d\n”, WED);

printf(“THU: %d\n”, THU);

printf(“FRI: %d\n”, FRI);

printf(“SAT: %d\n”, SAT);

return 0;

}

2. The following is one possible solution:

/* 23A02.c */

#include

#define MULTIPLY(val1, val2) ((val1) * (val2))

#define NO_ERROR 0

main(void)

{

int result;

result = MULTIPLY(2, 3);

33 067231861x AppxB 4.10.2000 11:05 AM Page 501

Answers to Quiz Questions and Exercises

501

printf(“MULTIPLY(2, 3) produces value of %d.\n”, result);

return NO_ERROR;

}

3. The following is one possible solution:

/* 23A03.c */

#include

#define UPPER_CASE 0

#define NO_ERROR 0

main(void)

{

#if UPPER_CASE

printf(“THIS LINE IS PRINTED OUT,\n”);

printf(“BECAUSE UPPER_CASE IS DEFINED.\n”);

#elif LOWER_CASE

printf(“This line is printed out,\n”);

printf(“because LOWER_CASE is defined.\n”);

#else

printf(“This line is printed out,\n”);

printf(“because neither UPPER_CASE nor LOWER_CASE is defined.\n”);

#endif

B

return NO_ERROR;

}

4. The following is one possible solution:

/* 23A04.c: */

#include

#define C_LANG ‘C’

#define B_LANG ‘B’

#define NO_ERROR 0

main(void)

{

#if C_LANG == ‘C’

#if B_LANG == ‘B’

#undef C_LANG

#define C_LANG “I know C language.\n”

#undef B_LANG

#define B_LANG “Also, I know BASIC.\n”

printf(“%s%s”, C_LANG, B_LANG);

#else

#undef C_LANG

#define C_LANG “I only know C language.\n”

printf(“%s”, C_LANG);

33 067231861x AppxB 4.10.2000 11:05 AM Page 502

502

Appendix B

#endif

#elif B_LANG == ‘B’

#undef B_LANG

#define B_LANG “I only know BASIC.\n”

printf(“%s”, B_LANG);

#else

printf(“I don’t know C or BASIC.\n”);

#endif

return NO_ERROR;

}

34 067231861x index 1/25/00 10:45 AM Page 503

INDEX

~ (bitwise complement

== (equal to operator),

Symbols

operator), 131

98

| (bitwise OR operator),

\ (escape character), 59

+= (addition assignment

131

%% format specifier, 79

operator), 93

^ (bitwise XOR opera-

> (greater than opera-

& (ampersand)

tor), 131

tor), 98

address-of operator,

{} (braces), 45, 48

>= (greater than or equal

177-179

if statement, 156

to operator), 98

bitwise AND operator,

if-else statement, 159

++ (increment operator),

131

[ ] (brackets), 190

96-98

<> (angle brackets), 32

*/ (closing comment

<< (left-shift operator),

-> (arrow operator),

mark), 29

133-135

unions, 335, 351

:? (conditional operator),

< (less than operator), 98

= (assignment operator),

135-136

<= (less than or equal to

92

-- (decrement operator),

operator), 98

* (asterisk)

96-98

&& (logical AND opera-

deference operator, 182

/= (division assignment

tor), 124-126

determining meaning,

operator), 93

! (logical NEGATION

182

. (dot operator), unions,

operator), 128-129

multiplication operator,

335-337, 351

|| (logical OR operator),

182

” (double quotes), 32-33,

126-127

pointers, 180

59

*= (multiplication assign-

ment operator), 93

34 067231861x index 1/25/00 10:45 AM Page 504

504

!= (not equal to operator)

!= (not equal to opera-

ftell() function,

built-in

tor), 98

374-378

main() functions,

\0 (null character), 198

sequential disk files,

306

/* (opening comment

374

naming, 308

mark), 29

accessing

replacing, 308

// (opening comment

array elements, indexes,

command-line, 305

mark), 30

190

receiving, 306-308

() (parentheses)

arrays, via pointers,

passing to functions,

if statement, 156

264-266

47-48, 305

placing around expres-

addition assignment

variable, processing,

sions, 419

operator (+=), 93

252-254

% (remainder operator),

address variables.
See

argv arguments, 306

43

pointers

arithmetic assignment

%= (remainder assign-

address-of operator (&),

operators, 92-95

ment operator), 93

177-179, 323

addition assignment

>> (right-shift operator),

addresses

(+=), 93

133-135

left value, 176

division assignment

; (semicolons), 28

memory, 343

(/=), 93

’ (single quotes), 59

algorithms, implement-

multiplication assign-

-= (subtraction assign-

ing, 305

ment (*=), 93

ment operator), 93

aligning output, 83-84

remainder assignment

- (subtraction operator),

allocating memory

(%=), 93

96

calloc() function,

subtraction assignment

- (unary minus operator),

286-288

(-=), 93

95

malloc() function,

arithmetic expressions,

19L02.exe executable,

280-283

#if directive, 406

318

American National

arithmetic operators,

Standards Institute.
See

43-44

ANSI

array data type, 424

angle brackets (<>), 32

array element references,

A

ANSI (American

191

National Standards

array subscript operator

access

Institute), 15

([ ]), 190

random

C standard, 15-16

arrays, 190

code example,

header files, 439

accessing via pointers,

375-378

applying static specifiers,

264-266

disk files, 374-377,

230-231

character, 190, 210-211

387

argc arguments, 306

displaying, 196-198

fseek() function,

argument lists, 47

initializing, 208-209

374-378

arguments

declaring, 190

argc, 306

argv, 306

34 067231861x index 1/25/00 10:45 AM Page 505

books

505

elements, 190

integers to structures,

binary operators, multi-

accessing, 190

315

plication (*), 182

initializing, 191-192

inter values to enum

binary streams, 356, 370

integers, 190

data types, 296, 300

Other books

The Visitor by K. A. Applegate
THE HAPPY HAT by Peter Glassman
The Unwelcomed Child by V. C. Andrews
Dark Secrets by Jessica Burnett
The Scream by John Skipper, Craig Spector
Devil's Touch by Tina Lindegaard
Dark Lie (9781101607084) by Springer, Nancy
Don't Breathe a Word by Jennifer McMahon
Lisette's List by Susan Vreeland


readsbookonline.com Copyright 2016 - 2024