实验5
task1_1
#include <stdio.h>
#define N 5
void input(int x[], int n);
void output(int x[], int n);
void find_min_max(int x[], int n, int *pmin, int *pmax);
int main() {
int a[N];
int min, max;
printf("录入%d个数据:\n", N);
input(a, N);
printf("数据是: \n");
output(a, N);
printf("数据处理...\n");
find_min_max(a, N, &min, &max);
printf("输出结果:\n");
printf("min = %d, max = %d\n", min, max);
return 0;
}
void input(int x[], int n) {
int i;
for(i = 0; i < n; ++i)
scanf("%d", &x[i]);
}
void output(int x[], int n) {
int i;
for(i = 0; i < n; ++i)
printf("%d ", x[i]);
printf("\n");
}
void find_min_max(int x[], int n, int *pmin, int *pmax) {
int i;
*pmin = *pmax = x[0];
for(i = 0; i < n; ++i)
if(x[i] < *pmin)
*pmin = x[i];
else if(x[i] > *pmax)
*pmax = x[i];
}
1.找出一组数据中的最小值和最大值
2.分别指向main函数中的min和max
task1_2
#include <stdio.h>
#define N 5
void input(int x[], int n);
void output(int x[], int n);
int *find_max(int x[], int n);
int main() {
int a[N];
int *pmax;
printf("录入%d个数据:\n", N);
input(a, N);
printf("数据是: \n");
output(a, N);
printf("数据处理...\n");
pmax = find_max(a, N);
printf("输出结果:\n");
printf("max = %d\n", *pmax);
return 0;
}
void input(int x[], int n) {
int i;
for(i = 0; i < n; ++i)
scanf("%d", &x[i]);
}
void output(int x[], int n) {
int i;
for(i = 0; i < n; ++i)
printf("%d ", x[i]);
printf("\n");
}
int *find_max(int x[], int n) {
int max_index = 0;
int i;
for(i = 0; i < n; ++i)
if(x[i] > x[max_index])
max_index = i;
return &x[max_index];
}
1.函数的功能是找到数据中的最大值，返回的是x[i]
2.可以，用执政变量代替 t
task2_1
#include <stdio.h>
#include <string.h>
#define N 80
int main() {
char s1[N] = "Learning makes me happy";
char s2[N] = "Learning makes me sleepy";
char tmp[N];
printf("sizeof(s1) vs. strlen(s1): \n");
printf("sizeof(s1) = %d\n", sizeof(s1));
printf("strlen(s1) = %d\n", strlen(s1));
printf("\nbefore swap: \n");
printf("s1: %s\n", s1);
printf("s2: %s\n", s2);
printf("\nswapping...\n");
strcpy(tmp, s1);
strcpy(s1, s2);
strcpy(s2, tmp);
printf("\nafter swap: \n");
printf("s1: %s\n", s1);
printf("s2: %s\n", s2);
return 0;
}
.大小为4字节；计算的是数组s1的大小；统计的是字符串的长度
2.不能， 操作改变了s[0]的地址
tasl2_2
#include <stdio.h>
#include <string.h>
#define N 80
int main() {
char *s1 = "Learning makes me happy";
char *s2 = "Learning makes me sleepy";
char *tmp;
printf("sizeof(s1) vs. strlen(s1): \n");
printf("sizeof(s1) = %d\n", sizeof(s1));
printf("strlen(s1) = %d\n", strlen(s1));
printf("\nbefore swap: \n");
printf("s1: %s\n", s1);
printf("s2: %s\n", s2);
printf("\nswapping...\n");
tmp = s1;
s1 = s2;
s2 = tmp;
printf("\nafter swap: \n");
printf("s1: %s\n", s1);
printf("s2: %s\n", s2);
return 0;
}1.字符串的地址；s1占的字节数；字符串的字符个数
2.可以
3.交换指针变量，没有
task3
#include <stdio.h>
int main() {
int x[2][4] = {{1, 9, 8, 4}, {2, 0, 4, 9}};
int i, j;
int *ptr1; // 指针变量，存放int类型数据的地址
int(*ptr2)[4]; // 指针变量，指向包含4个int元素的一维数组
printf("输出1: 使用数组名、下标直接访问二维数组元素\n");
for (i = 0; i < 2; ++i) {
for (j = 0; j < 4; ++j)
printf("%d ", x[i][j]);
printf("\n");
}
printf("\n输出2: 使用指针变量ptr1(指向元素)间接访问\n");
for (ptr1 = &x[0][0], i = 0; ptr1 < &x[0][0] + 8; ++ptr1, ++i) {
printf("%d ", *ptr1);
if ((i + 1) % 4 == 0)
printf("\n");
}
printf("\n输出3: 使用指针变量ptr2(指向一维数组)间接访问\n");
for (ptr2 = x; ptr2 < x + 2; ++ptr2) {
for (j = 0; j < 4; ++j)
printf("%d ", *(*ptr2 + j));
printf("\n");
}
return 0;
}
1.标志符ptr标示的语义是行指针变量
2.指针数组
task4
#include <stdio.h>
#define N 80
void replace(char *str, char old_char, char new_char); // 函数声明
int main() {
char text[N] = "Programming is difficult or not, it is a question.";
printf("原始文本: \n");
printf("%s\n", text);
replace(text, 'i', '*'); // 函数调用 注意字符形参写法，单引号不能少
printf("处理后文本: \n");
printf("%s\n", text);
return 0;
}
// 函数定义
void replace(char *str, char old_char, char new_char) {
int i;
while(*str) {
if(*str == old_char)
*str = new_char;
str++;
}
}
1.i换成*
2.可以
task5
#include <stdio.h>
#define N 80
char *str_trunc(char *str, char x);
int main() {
char str[N];
char ch;
while(printf("输入字符串："), gets(str) != NULL) {
printf("输入一个字符：");
ch = getchar();
printf("截断处理...\n");
str_trunc(str, ch); // 函数调用
printf("截断处理后的字符串：%s\n\n", str);
getchar();
}
return 0;
}
// 函数str_trunc定义
char *str_trunc(char *str, char x) {
char *p = str;
// 查找字符x第一次出现的位置
while (*p != '\0' && *p != x) {
p++;
}
// 如果找到x，则截断字符串
if (*p == x) {
*p = '\0';
}
return str;
}
task6
#include <stdio.h>
#include <string.h>
#include <ctype.h> // For isdigit() function
#define N 5
int check_id(char *str); // 函数声明
int main()
{
char *pid[N] = {"31010120000721656X",
"330106199600203301",
"53010220051126571",
"51010419921119797",
"53010220051126133Y"};
int i;
for (i = 0; i < N; ++i)
if (check_id(pid[i])) // 函数调用
printf("%s\t合法\n", pid[i]);
else
printf("%s\t不合法\n", pid[i]);
return 0;
}
// 函数定义
// 功能：检查指针str指向的身份证号码形式是否合法
// 形式合法，返回1，否则，返回0
int check_id(char *str) {
int len = strlen(str);
// 检查长度是否为18
if (len != 18) {
return 0;
}
// 检查前17位是否为数字
for (int i = 0; i < 17; i++) {
if (!isdigit(str[i])) {
return 0;
}
}
// 检查最后一位是否为数字或X
char last = str[17];
if (!(isdigit(last) || last == 'X')) {
return 0;
}
// 所有检查通过
return 1;
}
task7
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#define N 80
void encoder(char *str, int n); // Function declaration
void decoder(char *str, int n); // Function declaration
int main() {
char words[N];
int n;
printf("输入英文文本: ");
fgets(words, N, stdin);
words[strcspn(words, "\n")] = '\0'; // Remove newline character
printf("输入n: ");
scanf("%d", &n);
printf("编码后的英文字符: ");
encoder(words, n); // Function call
printf("%s\n", words);
printf("对编码后的英文字符解码: ");
decoder(words, n); // Function call
printf("%s\n", words);
return 0;
}
/* Function definition */
// Encodes the string by shifting letters n positions forward in the alphabet
void encoder(char *str, int n) {
for (int i = 0; str[i] != '\0'; i++) {
if (isalpha(str[i])) {
char base = isupper(str[i]) ? 'A' : 'a';
str[i] = base + (str[i] - base + n) % 26;
}
}
}
/* Function definition */
// Decodes the string by shifting letters n positions backward in the alphabet
void decoder(char *str, int n) {
for (int i = 0; str[i] != '\0'; i++) {
if (isalpha(str[i])) {
char base = isupper(str[i]) ? 'A' : 'a';
str[i] = base + (str[i] - base - n + 26) % 26;
}
}
}
task8
c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
// 用于qsort的字符串比较函数
int compare_strings(const void *a, const void *b) {
return strcmp(*(const char **)a, *(const char **)b);
}
int main(int argc, char *argv[]) {
// 检查是否有参数输入
if (argc < 2) {
printf("用法: %s 姓名1 姓名2 ...\n", argv[0]);
return 1;
}
// 对姓名进行排序（从argv[1]到argv[argc-1]）
qsort(argv + 1, argc - 1, sizeof(char *), compare_strings);
// 按排序后的顺序打印问候语
for (int i = 1; i < argc; ++i) {
printf("hello, %s\n", argv[i]);
}
return 0;
}
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