实验5

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#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 = 1; i < n; ++i)
        if (x[i] < *pmin)
            *pmin = x[i];
        else if (x[i] > *pmax)
            *pmax = x[i];
}

找到数组中的最大值和最小值

都指向x[0]的地址

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#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 = 1; i < n; ++i)
        if (x[i] > x[max_index])
            max_index = i;
    return &x[max_index];
}

返回的是x[]数组中最大值的地址

可以

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#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[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;
    system("pause");
}

sizeof计算的是占据的存储空间的大小

strlen计算的是字符串的长度（不计\0)

不能；等号左边的必须是可修改的左值,而s1是数组常量

交换

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.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;
}

字符串的首地址

sizeof是指针变量占据的空间，strlen是整个字符串的长度

可以；task2.1改变的是数组常量，task2.2是通过指针间接访问地址然后间接访问字符串

换的是首个字符的地址；没有

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.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: 使用指向元素的指针变量p间接访问二维数组元素\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: 使用指向一维数组的指针变量q间接访问二维数组元素\n");
    for (ptr2 = x; ptr2 < x + 2; ++ptr2) {
        for (j = 0; j < 4; ++j)
            printf("%d ", *(*ptr2 + j));
        printf("\n");
    }
    return 0;
}

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#define N 80
void replace(char* str, char old_char, char new_char); // 函数声明
int main() {
    char text[N] = "c 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);
    system("pause");
    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++;
    }
}

将字符串中的old_char全部换成new_char

可以，*str通过指针间接访问字符

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#define N 80
void str_trunc(char* str, char x);
int main() {
    char str[N];
    char ch;
    printf("输入字符串: ");
    gets(str);
    printf("输入一个字符: ");
    ch = getchar();
    printf("截断处理...\n");
    str_trunc(str, ch);
    printf("截断处理后的字符串: %s\n", str);
    system("pause");
}
void str_trunc(char* str, char x) {
    while (*str) {
        if (*str == x)
            *str = 0;
        str++;
    }
    return 0;
}

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include <string.h>
void sort(char* name[], int n);
int main() {
    char* course[4] = { "C Program",
    "C++ Object Oriented Program",
    "Operating System",
    "Data Structure and Algorithms" };
    int i;
    sort(course, 4);
    for (i = 0; i < 4; i++)
        printf("%s\n", course[i]);
    return 0;
}
void sort(char* name[], int n) {
    int i, j;
    char* tmp;
    for (i = 0; i < n - 1; ++i)
        for (j = 0; j < n - 1 - i; ++j)
            if (strcmp(name[j], name[j + 1]) > 0) {
                tmp = name[j];
                name[j] = name[j + 1];
                name[j + 1] = tmp;
            }
}

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include <string.h>
void sort(char* name[], int n);
int main() {
    char* course[4] = { "C Program",
    "C++ Object Oriented Program",
    "Operating System",
    "Data Structure and Algorithms" };
    int i;
    sort(course, 4);
    for (i = 0; i < 4; i++)
        printf("%s\n", course[i]);
    return 0;
}
void sort(char* name[], int n) {
    int i, j, k;
    char* tmp;
    for (i = 0; i < n - 1; i++) {
        k = i;
        for (j = i + 1; j < n; j++)
            if (strcmp(name[j], name[k]) < 0)
                k = j;
        if (k != i) {
            tmp = name[i];
            name[i] = name[k];
            name[k] = tmp;
        }
    }
}

冒泡交换的是位置，选择交换的是指针变量的值

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include <stdio.h>
#include <string.h>
#define N 5
int check_id(char* str); // 函数声明
int main()
{
    char* pid[N] = { "31010120000721656X",
    "330106199609203301",
    "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;
    else
    while (*str)
    {
        int i = 0, count = 0;
        for (i = 0; i < strlen(str); i++) {
            if ((str[i] >= 48 && str[i] <= 57) || str[i] == 'X')
                count++;
        }
            if (count == 18)
                return 1;
            else
                return 0;
    }
    
}

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#define N 80
void encoder(char* str); // 函数声明
void decoder(char* str); // 函数声明
int main() {
    char words[N];
    printf("输入英文文本: ");
    gets(words);
printf("编码后的英文文本: ");
encoder(words); // 函数调用
printf("%s\n", words);
printf("对编码后的英文文本解码: ");
decoder(words); // 函数调用
printf("%s\n", words);
return 0;
}
/*函数定义
功能：对s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，用其后的字符替换; 其中，z用a替换，Z用A替换
其它非字母字符，保持不变
*/
void encoder(char* str) {
    int i = 0;
    for (i = 0; i < strlen(str); i++)
    {
        if ((str[i] >= 'a' && str[i] <= 'y') || (str[i] >= 'A' && str[i] <= 'Y'))
            str[i] = str[i] + 1;
        else if (str[i] == 'z')
            str[i] = 'a';
        else if (str[i] == 'Z')
            str[i] = 'A';
        else
            str[i] = str[i];
    }

}
/*函数定义
功能：对s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，用其前面的字符替换; 其中，a用z替换，A用Z替换
其它非字母字符，保持不变
*/
void decoder(char* str) {
    int i = 0;
    for (i = 0; i < strlen(str); i++)
    {
        if ((str[i] >= 'b' && str[i] <= 'z') || (str[i] >= 'B' && str[i] <= 'Z'))
            str[i] = str[i] - 1;
        else if (str[i] == 'a')
            str[i] = 'z';
        else if (str[i] == 'A')
            str[i] = 'Z';
    }
}

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
int main(int argc, char* argv[]) {
    int i;
    for (i = 1; i < argc; ++i)
        printf("hello, %s\n", argv[i]);
    return 0;
}

 

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
int main(int argc, char* argv[]) {
    int i;
    for (i = 1; i < argc; ++i)
        printf("hello, %s\n", argv[i]);
    return 0;
}

 

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
void sort(char* name[], int n);
int main(int argc, char* argv[]) {
    int i;
    sort(argv, argc);
    for (i = 1; i < argc; ++i)
        printf("hello, %s\n", argv[i]);
    return 0;
}
void sort(char* name[], int n) {
    int i, j, k;
    char* tmp;
    for (i = 0; i < n - 1; i++) {
        k = i;
        for (j = i + 1; j < n; j++)
            if (strcmp(name[j], name[k]) < 0)
                k = j;
        if (k != i) {
            tmp = name[i];
            name[i] = name[k];
            name[k] = tmp;
        }
    }
}