由于电脑对随机函数的支持出了问题，所以只能做部分的题。。。
第一题
#include <stdio.h>
//既然不能使用全局变量，那就最初交的办法，指针构建函数之间的通信，搞起！
void critic(int *);
int main(void) {
int uints = 0;
int *ptr = &uints;
printf("How many pounds to a firkin of butter?\n");
scanf("%d", &uints);
while (uints != 56) critic(ptr);
printf("You must have looker it upp!\n");
return 0;
}
void critic(int *ptr) {
printf("No luck, my friend. Try again!\n");
scanf("%d", ptr);
}
第二题
CMAKElist：
cmake_minimum_required(VERSION 3.20)
project(C_Prime_Plus C)
set(CMAKE_C_STANDARD 11)
add_executable(C_Prime_Plus pel2-2a.h pel2-2a.c pel2-2b.c)
pel2-2a.h
#include <stdio.h>
//头文件存放函数原型
void get_info();
void show_info();
void set_mode(int);
pel2-2a.c
#include <stdio.h>
#include "pel2-2a.h"
static double distance; //文件作用域的内部链接变量
static double goal; //文件作用域的内部链接变量
static int mode; //文件作用域的内部链接变量
void set_mode(int x) {
if (x == 0 || x == 1) mode = x;
else printf("Invalid mode specified. Mode %d used.\n", mode);
}
void get_info() {
if (mode == 0) {
printf("Enter distance travled in kilometers: ");
scanf("%lf", &distance);
while (getchar() != '\n')continue;
printf("Enter fuel consumed in liters: ");
scanf("%lf", &goal);
while (getchar() != '\n')continue;
} else if (mode == 1) {
printf("Enter distance traveled in miles: ");
scanf("%lf", &distance);
while (getchar() != '\n')continue;
printf("Enter fuel consumed in gallon: ");
scanf("%lf", &goal);
while (getchar() != '\n')continue;
}
return;
}
void show_info() {
double a = goal / (distance / 100);
double b = distance / goal;
if (mode == 0) {
printf("Fuel consumption is %.2f liters per 100 km.\n", a);
} else if (mode == 1) {
printf("Fuel consumption is %.2f miles per gallon.\n", b);
}
}
pel2-2b.c
#include <stdio.h>
#include "pel2-2a.h"
int main(void) {
int mode; //这个mode变量是属于main()这个块作用域的，与另一个文件的mode变量没有关系。
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);
}
puts("Done!");
return 0;
}
第三题
CMAKElist：
cmake_minimum_required(VERSION 3.20)
project(C_Prime_Plus C)
set(CMAKE_C_STANDARD 11)
add_executable(C_Prime_Plus pel2-2a.h pel2-2a.c pel2-2b.c)
pel2-2a.h
#include <stdio.h>
//头文件存放函数原型
void set_mode(int x, int *ptr_mode);
void get_info(const int *ptr_mode, double *ptr_distance, double *ptr_goal) ;
void show_info(const int *ptr_mode, const double *ptr_distance, const double *ptr_goal);
pel2-2a.c
#include <stdio.h>
#include "pel2-2a.h"
void set_mode(int x, int *ptr_mode) {
if (x == 0 || x == 1) *ptr_mode = x;
else printf("Invalid mode specified. Mode %d used.\n", *ptr_mode);
}
void get_info(const int *ptr_mode, double *ptr_distance, double *ptr_goal) {
if (*ptr_mode == 0) {
printf("Enter distance travled in kilometers: ");
scanf("%lf", ptr_distance);
while (getchar() != '\n')continue;
printf("Enter fuel consumed in liters: ");
scanf("%lf", ptr_goal);
while (getchar() != '\n')continue;
} else if (*ptr_mode == 1) {
printf("Enter distance traveled in miles: ");
scanf("%lf", ptr_distance);
while (getchar() != '\n')continue;
printf("Enter fuel consumed in gallon: ");
scanf("%lf", ptr_goal);
while (getchar() != '\n')continue;
}
}
void show_info(const int *ptr_mode, const double *ptr_distance, const double *ptr_goal) {
double a = *ptr_goal / (*ptr_distance / 100);
double b = *ptr_distance / *ptr_goal;
if (*ptr_mode == 0) {
printf("Fuel consumption is %.2f liters per 100 km.\n", a);
} else if (*ptr_mode == 1) {
printf("Fuel consumption is %.2f miles per gallon.\n", b);
}
}
pel2-2b.c
#include <stdio.h>
#include "pel2-2a.h"
int main(void) {
double distance, goal;
int select, mode;
double *ptr_distance = &distance;
double *ptr_goal = &goal;
int *ptr_mode = &mode;
printf("Enter 0 for metric mode, 1 for US mode: ");
scanf("%d", &select);
while (select >= 0) {
set_mode(select, ptr_mode);
get_info(ptr_mode, ptr_distance, ptr_goal);
show_info(ptr_mode, ptr_distance, ptr_goal);
printf("Enter 0 for metric mode, 1 for US mode");
printf("(-1 to quit)");
scanf("%d", &select);
}
puts("Done!");
return 0;
}
第四题
#include <stdio.h>
static int count = 0; //使用静态内存的内部链接。
void function(void);
int main(void) {
for (int i = 0; i < 10; ++i) {
function();
}
printf("%d", count);
return 0;
}
void function(void) {
count++;
}
第八题
#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, 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): ");
}
puts("Done!");
return 0;
}
int *make_array(int elem, int val) {
int *ptr;
ptr = (int *) malloc(sizeof(int) * elem);
for (int i = 0; i < elem; ++i) {
ptr[i] = val;
}
return ptr;
}
void show_array(const int ar[], int n) {
for (int i = 0; i < n; ++i) {
printf("%d ", ar[i]);
if ((i + 1) % 8 == 0) putchar('\n');
}
putchar('\n');
}
第九题
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define LEN 20
static char ar[LEN];//临时数组
void words(int);
int main(void) {
int num;
puts("How many words do you wish to enter?");
scanf("%d", &num);
words(num);
printf("Done!");
return 0;
}
void words(int n) {
int len;
printf("Enter 5 words now:\n");
char **ptr = (char **) malloc(n * sizeof(char *));
for (int i = 0; i < n; ++i) {
scanf("%s", ar); //scanf每次都会先把对象擦掉再写入
len = strlen(ar);
ptr[i] = (char *) malloc((len + 1) * sizeof(char)); //len+1是为了留出空白符的位置。
strncpy(ptr[i], ar, len); //将用户输入的单词从临时数组复制到要用到的空间中。
}
for (int i = 0; i < n; ++i) {
puts(ptr[i]);
free(ptr[i]);
ptr[i] = NULL; //虽然清除了内存空间，但是指针依然存在，不要让他成为野指针。
}
free(ptr);
ptr = NULL; //虽然清除了内存空间，但是指针依然存在，不要让他成为野指针。
return;
}
