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("¼Èë%d¸öÊý¾Ý:\n", N);
    input(a, N);

    printf("Êý¾ÝÊÇ: \n");
    output(a, N);

    printf("Êý¾Ý´¦Àí...\n");
    find_min_max(a, N, &min, &max);

    printf("Êä³ö½á¹û:\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_s("%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.找到最小值和最大值

2.最小值，最大值

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("¼Èë%d¸öÊý¾Ý:\n", N);
    input(a, N);

    printf("Êý¾ÝÊÇ: \n");
    output(a, N);

    printf("Êý¾Ý´¦Àí...\n");
    pmax = find_max(a, N);

    printf("Êä³ö½á¹û:\n");
    printf("max = %d\n", *pmax);

    return 0;
}

void input(int x[], int n) {
    int i;

    for (i = 0; i < n; ++i)
        scanf_s("%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.查找数组中最大值，返回最大值地址

2.可以

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_s(tmp,sizeof(tmp), s1);
    strcpy_s(s1, sizeof(s1), s2);
    strcpy_s(s2, sizeof(s2), tmp);

    printf("\nafter swap: \n");
    printf("s1: %s\n", s1);
    printf("s2: %s\n", s2);

    return 0;
}

1.80，数组大小 ，字符串有效字符个数

2.不能，数组名是常量指针

3.交换

task2.2

#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.L的地址，str1占用的字节数，有效字符数
2.可以，该写法是将L的地址赋值给了指针s1，2_1中的line6是将字符串赋值给 了数组s1
3.交换了指针s1和s2指向的地址，内存中未交换

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;
}

指向含4个int类型元素的数组的指针

包含4个指向int类型的指针的数组

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.将old_char替换成new_char

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;
}
char* str_trunc(char *str, char x) {
    char *p = str;
    while (*p != '\0' && *p != x) {
        p++;
    }
    if (*p != '\0') {
        *p = '\0';
    }
    return str;
}
// 函数str_trunc定义
// 功能: 对字符串作截断处理，把指定字符自第一次出现及其后的字符全部删除, 并返回字符串地址
// 待补足...
// xxx

处理换行符

task6

#include <stdio.h>
#include <string.h>
#define N 5

int check_id(char* str); // 函数声明

int main()
{
    char* pid[N] = { "31010120000721656X",
                    "3301061996X0203301",
                    "53010220051126571",
                    "510104199211197977",
                    "53010220051126133Y" };
    int i;

    for (i = 0; i < N; ++i)
        if (check_id(pid[i])) // 函数调用
            printf("%s\tTrue\n", pid[i]);
        else
            printf("%s\tFalse\n", pid[i]);

    return 0;
}

// 函数定义
// 功能: 检查指针str指向的身份证号码串形式上是否合法
// 形式合法，返回1，否则，返回0
int check_id(char* str) {
    if (strlen(str) != 18) {
        return 0;
    }
    for (int i = 0; i < 17; i++) {
        if (str[i] < '0' || str[i]>'9') {
            return 0;
        }
    }
    char last = str[17];
    if (last != 'X' && (str[17] < '0' || str[17]>'9')) {
        return 0;
    }
    return 1;
}

 

task7

#include <stdio.h>
#define N 80
void encoder(char* str, int n); // 函数声明
void decoder(char* str, int n); // 函数声明
int main() {
    char words[N];
    int n;
    printf("输入英文文本: ");
    gets(words);
    printf("输入n: ");
    scanf_s("%d", &n);
    printf("编码后的英文文本: ");
    encoder(words, n); 
    printf("%s\n", words);
    printf("对编码后的英文文本解码: ");
    decoder(words, n); // 函数调用
    printf("%s\n", words);
    return 0;
}
/*函数定义
功能：对str指向的字符串进行编码处理
编码规则：
对于a~z或A~Z之间的字母字符，用其后第n个字符替换; 其它非字母字符，保持不变
*/
void encoder(char* str, int n) {
    while (*str != '\0') {
        if (*str >= 'a' && *str <= 'z') {
            *str = 'a' + (*str - 'a' + n) % 26;
        }
        else if (*str >= 'A' && *str <= 'Z') {
            *str = 'A' + (*str - 'A' + n) % 26;
        }
        str++;
    }
}
/*函数定义
功能：对str指向的字符串进行解码处理
解码规则：
对于a~z或A~Z之间的字母字符，用其前面第n个字符替换; 其它非字母字符，保持不变
*/
void decoder(char* str, int n) {
    while (*str != '\0') {
        if (*str >= 'a' && *str <= 'z') {
            *str = 'a' + (*str - 'a' - n + 26) % 26;
        }
        else if (*str >= 'A' && *str <= 'Z') {
            *str = 'A' + (*str - 'A' - n + 26) % 26;
        }
        str++;
    }
}

 

task8

#include <stdio.h>
#include<string.h>
void sort(int n, char* s[]);

int main(int argc, char* argv[]) {
    int i;

    sort(argc - 1, argv + 1);


    for (i = 1; i < argc; ++i)
        printf("hello, %s\n", argv[i]);

    return 0;
}

void sort(int n, char* s[]) {
    int i, j;
    char* t;
    for (i = 0; i < n - 1; i++) {


        for (j = 0; j < n - i - 1; j++) {

            if (strcmp(s[j], s[j + 1]) > 0) {

                t = s[j];
                s[j] = s[j + 1];
                s[j + 1] = t;
            }
        }
    }
}