C Primer Plus Sixth Edition Programming Exercise
Selected Answers
ROWS); putchar('\\n'); times2(stuff, ROWS); showarr2(stuff, ROWS);
return 0; }
void times2(int ar[][COLS], int r) {
int row, col;
for (row = 0; row < r; row++) for (col = 0; col < COLS; col++) ar[row][col] *= 2; }
void showarr2(int ar[][COLS], int r) {
int row, col;
for (row = 0; row < r; row++)
{ for (col = 0; col < COLS; col++) printf(\
ar[row][col]); putchar('\\n'); } }
PE 10---14
/* Programming Exercise 10-14 */ #include
void store(double ar[], int n);
double average2d(int rows, int cols, double ar[rows][cols]); double max2d(int rows, int cols, double ar[rows][cols]); void showarr2(int rows, int cols, double ar[rows][cols]); double average(const double ar[], int n);
int main(void) { double
stuff[ROWS][COLS]; int row;
for (row = 0; row < ROWS; row++) {
printf(\store(stuff[row], COLS); } printf(\contents:\\n\
showarr2(ROWS, COLS, stuff);
for (row = 0; row < ROWS; row++)
printf(\printf(\
printf(\return 0;
} void store(double ar[], int n)
{ int i;
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C Primer Plus Sixth Edition Programming Exercise
Selected Answers
for (i = 0; i < n; i++) {
printf(\scanf(\ }
} double average2d(int rows, int cols, double ar[rows][cols]) { int r, c; double sum = 0.0;
for (r = 0; r < rows; r++) for (c = 0; c < cols; c++) sum += ar[r][c]; if (rows * cols > 0) return sum / (rows * cols); else return 0.0; }
double max2d(int rows, int cols, double ar[rows][cols]) { int r, c; double max = ar[0][0];
for (r = 0; r < rows;
r++) for (c = 0; c < cols; c++) if (max <
ar[r][c]) max = ar[r][c]; return max; }
void showarr2(int rows, int cols, double ar[rows][cols]) {
int row, col;
for (row = 0; row < rows; row++) { for (col = 0; col < cols; col++) printf(\
ar[row][col]); putchar('\\n'); } }
double average(const double ar[], int n) { int i; double sum = 0.0;
for (i = 0; i < n; i++) sum += ar[i]; if (n > 0) return sum / n; else return 0.0; }
Chapter 11
Programming Exercises
PE 11---1
/* Programming Exercise 11-1 */ #include
int main(void) { char input[LEN]; char *check; check = getnchar(input, LEN - 1); if (check == NULL) puts(\failed.\
puts(input); puts(\return 0;
22
C Primer Plus Sixth Edition Programming Exercise
Selected Answers
}
char * getnchar(char * str, int n) { int i; int ch;
for (i = 0; i < n; i++) { ch = getchar(); if (ch != EOF)
str[i] = ch; else break; } if (ch == EOF) return NULL; else { str[i] = '\\0'; return str; } }
PE 11---3
/* Programming Exercise 11-3 */ #include
main(void) { char input[LEN]; while (getword(input) != NULL)
puts(input); puts(\return 0; }
#include
char * getword(char * str)
{ int ch; char * orig = str; // skip over initial whitespace while ((ch = getchar()) != EOF && isspace(ch)) continue; if (ch == EOF) return NULL; else
*str++ = ch; // first character in word // get rest of word
while ((ch = getchar()) != EOF && !isspace(ch)) *str++ = ch; *str = '\\0'; if (ch == EOF) return NULL; else { while (ch != '\\n') ch = getchar(); return orig; } }
PE 11---6
/* Programming Exercise 11-6 */ #include
_Bool is_within(const char * str, char c); char * s_gets(char * st, int n);
int main(void) { char
input[LEN]; char
ch; int found;;
23
C Primer Plus Sixth Edition Programming Exercise
Selected Answers
printf(\
while (s_gets(input, LEN) && input[0] != '\\0') {
printf(\ch = getchar(); while (getchar() != '\\n') continue; found =
is_within(input, ch); if (found == 0)
printf(\else
printf(\printf(\ }
puts(\ return 0; }
_Bool is_within(const char * str, char ch) {
while (*str != ch && *str != '\\0') str++;
return *str; /* = 0 if \\0 reached, non-zero otherwise */ } char * s_gets(char * st, int n) { char *
ret_val; char * find;
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---8
/* Programming Exercise 11-8 */ #include
char * string_in(const char * s1, const char * s2); int main(void) {
char orig[LEN] = \char * find; puts(orig); find = string_in(orig, \if (find) puts(find); else puts(\find = string_in(orig, \if (find) puts(find); else
puts(\ return 0; }
24
C Primer Plus Sixth Edition Programming Exercise
Selected Answers
#include
char * string_in(const char * s1, const char * s2) {
int l2 = strlen(s2);
int tries; /* maximum number of comparisons */ int nomatch = 1; /* set to 0 if match is found */
tries = strlen(s1) + 1 - l2; if (tries > 0)
while (( nomatch = strncmp(s1, s2, l2)) && tries--) s1++; if (nomatch) return NULL; else return (char *) s1; /* cast const away */ }
PE 11---10
/* Programming Exercise 11-10 */ #include
#include
drop_space(char * s); char * s_gets(char * st, int n);
int main(void) {
char orig[LEN];
puts(\less:\'\\0')
{ drop_space(orig); puts(orig);
puts(\ }
puts(\return 0; }
int drop_space(char * s) { char * pos;
while (*s) /* or while (*s != '\\0') */ {
if (*s == ' ')
{ pos = s; do {
*pos = *(pos + 1); pos++; } while (*pos); } else s++; } }
char * s_gets(char * st, int n) { char *
ret_val; char * find;
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（完整word版）CPrimerPlus第6版编程练习答案（已下载）
