（完整word版）CPrimerPlus第6版编程练习答案（已下载）

C Primer Plus Sixth Edition Programming Exercise

Selected Answers

ret_val = fgets(st, n, stdin); if (ret_val) {

find = strchr(st, '\\n'); // look for newline if (find) // if the address is not NULL, *find = '\\0'; // place a null character there else

while (getchar() != '\\n') continue; }

return ret_val; }

PE 11---12

/* pe11-12.c -- counts words and certain characters */ /* Programming Exercise 11-11 */ #include

#include // for isspace()

#include // for bool, true, false int main(void) {

char c; // read in character int

low_ct = 0; // number of lowercase characters

int up_ct = 0; // number of uppercase characters int dig_ct = 0; // number of digits int n_words = 0; // number of words

int punc_ct = 0; // number of punctuation marks bool inword = false; // == true if c is in a word

printf(\while ((c = getchar()) != EOF)

{ if (islower(c)) low_ct++; else if

(isupper(c)) up_ct++; else if (isdigit(c)) dig_ct++; else if (ispunct(c))

punc_ct++; if (!isspace(c) && !inword) {

inword = true; // starting a new word n_words++; // count word }

if (isspace(c) && inword)

inword = false; // reached end of word }

printf(\ \n_words,low_ct,up_ct, dig_ct, punc_ct); return 0; }

PE 11---14

/* Programming Exercise 11-14 */ #include

#include /* for atof() */ #include /* for pow() */ int main(int argc, char *argv[])

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C Primer Plus Sixth Edition Programming Exercise

Selected Answers

{

double num, exp; if (argc != 3)

printf(\else { num = atof(argv[1]); exp = atof(argv[2]);

printf(\ } return 0; }

PE 11---16

/* Programming Exercise 11-16 */ #include #include

int main(int argc, char *argv[])

{ char mode =

'p'; int ok = 1; int ch;

if (argc > 2) {

printf(\ok = 0; /* skip processing input */ }

else if (argc == 2) {

if (argv[1][0] != '-') {

printf(\ok = 0; } else switch(argv[1][1])

{ case

'p' : case 'u' :

case 'l' : mode = argv[1][1]; break;

default : printf(\printf(\ } } if (ok)

while ((ch = getchar() ) != EOF) {

switch(mode) {

case 'p' : putchar(ch); break;

case 'u' : putchar(toupper(ch)); break;

case 'l' : putchar(tolower(ch)); } }

return 0; }

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Chapter 12

C Primer Plus Sixth Edition Programming Exercise

Selected Answers

Programming Exercises

PE 12---1

/* pe12-1.c -- deglobalizing global.c */ /* Programming Exercise 12-1 */ /* one of several approaches */ #include void critic(int * u); int main(void) {

int units; /* units now local */

printf(\butter?\\n\( units != 56) critic(&units);

printf(\return 0; }

void critic(int * u) {

printf(\scanf(\}

// or use a return value: // units = critic();

// and have critic look like this: /* int

critic(void) { int u;

printf(\scanf(\} */

// or have main() collect the next value for units

PE 12---3

//pe12-3a.h

#define METRIC 0 #define US 1

#define USE_RECENT 2

void check_mode(int *pm);

void get_info(int mode, double * pd, double * pf); void show_info(int mode, double distance, double fuel);

// pe12-3a.c

// compile with pe12-3b.c #include #include \

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C Primer Plus Sixth Edition Programming Exercise

Selected Answers

void check_mode(int *pm) {

if (*pm != METRIC && *pm != US)

{ printf(\*pm); printf(\ *pm = USE_RECENT; } }

void get_info(int mode, double * pd, double * pf) {

if (mode == METRIC)

printf(\else

printf(\scanf(\

printf(\else

printf(\scanf(\}

void show_info(int mode, double distance, double fuel) {

printf(\if (mode == METRIC)

printf(\else

printf(\}

// pe12-3b.c

// compile with pe12-3a.c #include

#include \main(void)

{ int mode; int prev_mode = METRIC; double distance, fuel;

printf(\scanf(\

{ check_mode(&mode); if (mode ==

USE_RECENT) mode = prev_mode; prev_mode = mode; get_info(mode, &distance, &fuel); show_info(mode, distance, fuel); printf(\for metric mode, 1 for US mode\quit): \ }

printf(\ return 0; }

PE 12---5

/* pe12-5.c */

#include #include

void print(const int array[], int limit); void sort(int array[], int limit);

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C Primer Plus Sixth Edition Programming Exercise

Selected Answers

#define SIZE 100 int main(void)

{ int i; int arr[SIZE];

for (i = 0; i < SIZE; i++) arr[i] = rand() % 10 + 1; puts(\print(arr,SIZE); sort(arr,SIZE);

puts(\print(arr,SIZE); return 0; }

/* sort.c -- sorts an integer array in decreasing order */ void sort(int array[], int limit) {

int top, search, temp;

for (top = 0; top < limit -1; top++)

for (search = top + 1; search < limit; search++) if (array[search] > array[top]) {

temp = array[search]; array[search] = array[top]; array[top] = temp; } }

/* print.c -- prints an array */ void print(const int array[], int limit) {

int index;

for (index = 0; index < limit; index++) {

printf(\if (index % 10 == 9) putchar('\\n'); }

if (index % 10 != 0) // if last line not complete putchar('\\n'); }

PE 12---7

/* pe12-7.c */ #include

#include /* for srand() */

#include /* for time() */ int rollem(int);

int main(void) {

int dice, count, roll; int sides; int set, sets;

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