//本博主所写的代码仅为阅读者提供参考;
//若有不足之处请提出，博主会尽所能修改;
//附上课后编程练习题目;
//若是对您有用的话请点赞或分享提供给它人;
//12.9 - 1.c
#include <stdio.h>
void critic(int *units);
int main(void)
{
int units;
printf("How many pounds to a firkin of butter?\n");
scanf("%d", &units);
while (units != 56)
{
critic(&units);
}
printf("You must have looked it up!\n");
return 0;
}
void critic(int *units)
{
printf("No luck, my friend. Try again.\n");
scanf("%d", units);
return;
}
//-------------
//12.9 - 2.c
//注意:要分成多个编译单元进行同时编译；
//----pe12-2a.h-----;
void set_mode(int n);
void get_info(void);
void show_info(void);
//------------------;
//----pe12-2b.c-----;
#include <stdio.h>
#include "pe12-2a.h"
int main(void)
{
int mode;
printf("Enter 0 for metric mode, 1 for US mode:");
scanf("%d", &mode);
while (mode >= 0)
{
set_mode(mode);
get_info();
show_info();
printf("Enter 0 for metric mode, 1 for US mode");
printf(" (-1 to quit): ");
scanf("%d", &mode);
}
printf("Done.\n");
return 0;
}
//------------------;
//----pe12-2a.c-----;
#include <stdio.h>
static int mode;
static double range;
static double fuel;
void set_mode(int n)
{
if (n > 1)
{
printf("Invalid mode specified. Mode %s used.\n",
(0 == mode) ? "0(metric)" : "1(US)");
}
else
{
mode = n;
}
return;
}
void get_info(void)
{
if (0 == mode)
{
printf("Enter distance traveled in kilometers: ");
}
else
{
printf("Enter distance traveled in miles: ");
}
scanf("%lf", &range);
if (0 == mode)
{
printf("Enter fuel consumed in liters: ");
}
else
{
printf("Enter fuel consumed in gallons: ");
}
scanf("%lf", &fuel);
return;
}
void show_info(void)
{
if (0 == mode)
{
printf("Fuel consumption is %.2lf liters per 100km.\n",
(fuel / range) * 100);
}
else
{
printf("Fuel consumption is %.1lf miles per gallon.\n",
range / fuel);
}
return;
}
//------------------;
//-------------
//12.9 - 3.c
//注意:要分成多个编译单元进行同时编译；
//----pe12-2a.h-----;
void set_mode(int *mode, int *n);
void get_info(int mode, double *range, double *fuel);
void show_info(int mode, double range, double fuel);
//------------------;
//----pe12-2b.c-----;
#include <stdio.h>
#include "pe12-2a.h"
int main(void)
{
int temp, mode;
double range, fuel;
printf("Enter 0 for metric mode, 1 for US mode:");
scanf("%d", &mode);
temp = mode;
while (mode >= 0)
{
set_mode(&mode, &temp);
get_info(temp, &range, &fuel);
show_info(temp, range, fuel);
printf("Enter 0 for metric mode, 1 for US mode");
printf(" (-1 to quit): ");
scanf("%d", &mode);
}
printf("Done.\n");
return 0;
}
//------------------;
//----pe12-2a.c-----;
#include <stdio.h>
void set_mode(int *mode, int *n)
{
if (*mode > 1)
{
printf("Invalid mode specified. Mode %s used.\n",
(0 == *n) ? "0(metric)" : "1(US)");
}
else
{
*n = *mode;
}
return;
}
void get_info(int mode, double *range, double *fuel)
{
if (0 == mode)
{
printf("Enter distance traveled in kilometers: ");
}
else
{
printf("Enter distance traveled in miles: ");
}
scanf("%lf", range);
if (0 == mode)
{
printf("Enter fuel consumed in liters: ");
}
else
{
printf("Enter fuel consumed in gallons: ");
}
scanf("%lf", fuel);
return;
}
void show_info(int mode, double range, double fuel)
{
if (0 == mode)
{
printf("Fuel consumption is %.2lf liters per 100 km.\n",
(fuel / range) * 100);
}
else
{
printf("Fuel consumption is %.1lf miles per gallon.\n",
range / fuel);
}
return;
}
//------------------;
//-------------
//12.9 - 4.c
#include <stdio.h>
static int count = 0;
int counter(void);
int main(void)
{
int i, j, k;
printf("请输入一个正整数:");
scanf("%d", &i);
for (j = 1; j <= i; j++)
{
printf("count = %d\n", counter());
}
printf("函数总共被调用了%d次\n", count);
return 0;
}
int counter(void)
{
return ++count;
}
//-------------
//12.9 - 5.c
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#define LEN 100
void sort(int a[], int n);
void show_array(const int a[], int n);
int main(void)
{
int i, a[LEN];
srand((unsigned int)time(0));
for (i = 0; i < LEN; i++)
{
a[i] = rand() % 10 + 1;
}
printf("最初的%d个数是:\n", LEN);
show_array(a, LEN);
sort(a, LEN);
printf("\n降序排序后的%d个数是:\n", LEN);
show_array(a, LEN);
return 0;
}
void sort(int a[], int n)
{
int i, j, t;
for (i = 0; i < n - 1; i++)
{
for (j = i + 1; j < n; j++)
{
if (a[i] < a[j])
{
t = a[j];
a[j] = a[i];
a[i] = t;
}
}
}
return;
}
void show_array(const int a[], int n)
{
int i;
for (i = 0; i < n; i++)
{
printf("%-3d", a[i]);
}
putchar('\n');
return;
}
//-------------
//12.9 - 6.c
//也可用标准库中的rand和srand;
//本程序用的是书上所说明的2个函数的具体实现;
//便于充分理解rand和srand两个函数;
#include <stdio.h>
#define N 10
#define LEN 1000
int myrand(void);
void mysrand(unsigned int seed);
static unsigned long int next = 1;
int main(void)
{
int i, temp, a[N + 1];
unsigned int seeds;
for (seeds = 1; seeds <= N; seeds++)
{
printf("第%d次生成随机数:\n", seeds);
mysrand(seeds);
for (i = 0; i < N + 1; i++)
{
a[i] = 0;
}
for (i = 0; i < LEN; i++)
{
temp = myrand() % 10 + 1;
a[temp]++;
}
for (i = 1; i < N + 1; i++)
{
printf("%d出现了%d次\n", i, a[i]);
}
printf("随机数总数:%d个\n\n", LEN);
}
return 0;
}
int myrand(void)
{
//↑rand函数的实现;
next = next * 1103515245 + 12345;
return (unsigned int)(next / 65536) % 32768;
}
void mysrand(unsigned int seed)
{
//↑srand函数的实现;
next = seed;
return;
}
//-------------
//12.9 - 7.c
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int rollem(int sides);
int main(void)
{
int dice, count, roll;
int sides;
int set, sets;
srand((unsigned int)time(0));
printf("Enter the number of sets.\nEnter q to stop: ");
while (scanf("%d", &sets) == 1)
{
printf("How many sides and how many dice?\n");
printf("Please two integers: ");
if (scanf("%d %d", &sides, &dice) != 2)
{
puts("Not integers -- terminating input loop.");
break;
}
printf("Here are %d sets of %d %d-sided throws.\n", sets, dice, sides);
for (set = 0; set < sets; set++)
{
for (roll = 0, count = 0; count < dice; count++)
{
roll += rollem(sides);
}
printf("%-3d", roll);
if (0 == (set + 1) % 8)
{
putchar('\n');
}
}
printf("\nHow many sets? Enter q to stop: ");
}
puts("GOOD FORTUNE TO YOU!\n");
return 0;
}
int rollem(int sides)
{
return rand() % sides + 1;
}
//-------------
//12.9 - 8.c
#include <stdio.h>
#include <stdlib.h>
int *make_array(int elem, int val);
void show_array(const int ar[], int n);
int main(void)
{
int *pa;
int size;
int value;
printf("Enter the number of elements: ");
while (scanf("%d", &size) == 1 && size > 0)
{
printf("Enter the initialization value: ");
scanf("%d", &value);
pa = make_array(size, value);
if (pa)
{
show_array(pa, size);
free(pa);
}
printf("Enter the number of elements (<1 to quit): ");
}
printf("Done.\n");
return 0;
}
int *make_array(int elem, int val)
{
int i;
int *pt;
pt = (int *)malloc(elem * sizeof(int));
if (NULL == pt)
{
printf("Memory allocation failed!\n");
exit(EXIT_FAILURE);
}
printf("Output %d numbers:\n", val);
for (i = 0; i < elem; i++)
{
pt[i] = val;
}
return pt;
}
void show_array(const int ar[], int n)
{
int i;
for (i = 0; i < n; i++)
{
printf("%d ", ar[i]);
if (0 == (i + 1) % 8)
{
putchar('\n');
}
}
putchar('\n');
return;
}
//-------------
//12.9 - 9.c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define LEN 100
int main(void)
{
char **pt;
char temp[LEN];
int i, n, length;
printf("How many words do you wish to enter? ");
scanf("%d", &n);
pt = (char **)malloc(n * sizeof(char *));
if (NULL == pt)
{
printf("Memory allocation failed!\n");
exit(EXIT_FAILURE);
}
printf("Enter %d words now:", n);
for (i = 0; i < n; i++)
{
scanf("%99s", temp);
length = strlen(temp) + 1;
//↑+1便于保存空字符'\0';
pt[i] = (char *)malloc(length * sizeof(char));
//↑使用malloc分配足够的存储空间来存储单词;
if (NULL == pt[i])
{
printf("Memory allocation failed!\n");
exit(EXIT_FAILURE);
}
strcpy(pt[i], temp);
//↑从临时数组中把单词拷贝到动态分配的存储空间中;
}
printf("Here are your words:\n");
for (i = 0; i < n; i++)
{
puts(pt[i]);
free(pt[i]);
pt[i] = NULL;
}
free(pt);
pt = NULL;
//↑指针仍然指向malloc分配的存储空间;
//↑因此令指针指向NULL后防止内存滥用;
return 0;
}
//-------------
//----------------------------2020年4月4日 -------------------------------
//致敬英雄，缅怀同胞，愿山河无恙，人间皆安！