7

1

源代码

#include <stdio.h>

#define N 80
#define M 100

typedef struct {
    char name[N];       // 书名
    char author[N];     // 作者
} Book;

void write();
void read();

int main() {
    printf("测试1: 把图书信息写入文本文件\n");
    write();

    printf("\n测试2: 从文本文件读取图书信息, 打印输出到屏幕\n");
    read();
    getchar();
    getchar();
    return 0;
}

void write() {
    Book x[] = { {"《雕塑家》", "斯科特.麦克劳德"},
                  {"《灯塔》", "克里斯多夫.夏布特"},
                  {"《人的局限性》", "塞缪尔.约翰生"}, 
                  {"《永不停步：玛格丽特.阿特伍德传》", "罗斯玛丽.沙利文"},
                  {"《大地之上》", "罗欣顿·米斯特里"}, 
                  {"《上学记》", "何兆武"}, 
                  {"《命运》", "蔡崇达"} };
    int n, i;
    FILE *fp;

    // 计算数组x中元素个数
    n = sizeof(x) / sizeof(x[0]);       
    
    // 以写的方式打开文本文件data1.txt 
    fp = fopen("data1.txt", "w");
    
    // 如果打开文件失败，输出提示信息并返回 
    if(fp == NULL) {
        printf("fail to open file to write\n");
        return;
    }
    
    // 将结构体数组x中的图书信息格式化写到fp指向的文件data1.txt
    for(i = 0; i < n; ++i)
        fprintf(fp, "%-40s %-20s\n", x[i].name, x[i].author);
    
    fclose(fp);
}

void read() {
    Book x[M]; 
    int i, n;
    int number;
    
    FILE *fp;
    
    // 以读的方式打开文本文件data1.txt 
    fp = fopen("data1.txt", "r");
    
    // 如果打开文件失败，输出提示信息并返回 
    if(fp == NULL) {
        printf("fail to open file to read\n");
        return;
    }
    
    // 从文件中读取图书信息，保存到结构体数组x中
   i = 0;
    while(!feof(fp)) {
        number = fscanf(fp, "%s%s", x[i].name, x[i].author);
        if(number != 2)
            break;
        i++;
    }
    n = i;

    // 将图书信息打印输出到屏幕上
    for(i = 0; i < n; ++i)
        printf("%d. %-40s%-20s\n", i+1, x[i].name, x[i].author);
    
    fclose(fp);
}

结果

存在换行符，会多读取一次。

2

源代码

#include <stdio.h>

#define N 80
#define M 100

typedef struct {
    char name[N];       // 书名
    char author[N];     // 作者
} Book;

void write();
void read();

int main() {
    printf("测试1: 把图书信息以数据块方式写入二进制文件\n");
    write();

    printf("\n测试2: 从二进制文件读取图书信息, 打印输出到屏幕\n");
    read();

    return 0;
}

void write() {
    Book x[] = { {"《雕塑家》", "斯科特.麦克劳德"},
                  {"《灯塔》", "克里斯多夫.夏布特"},
                  {"《人的局限性》", "塞缪尔.约翰生"}, 
                  {"《永不停步：玛格丽特.阿特伍德传》", "罗斯玛丽.沙利文"},
                  {"《大地之上》", "罗欣顿·米斯特里"}, 
                  {"《上学记》", "何兆武"}, 
                  {"《命运》", "蔡崇达"} };
    int n;
    FILE *fp;

    // 计算数组x中元素个数
    n = sizeof(x) / sizeof(x[0]);     
    
    // 以写的方式打开二进制文件data2.dat
    fp = fopen("data2.dat", "wb");
    
    // 如果打开文件失败，输出提示信息并返回 
    if(fp == NULL) {
        printf("fail to open file to write\n");
        return;
    }
    
    // 将结构体数组x中的图书信息以数据块方式写入二进制文件data2.dat
    fwrite(x, sizeof(Book), n, fp);
    
    fclose(fp);
}

void read() {
    Book x[M]; 
    int i, n;
    int number;
    
    FILE *fp;
    
    // 以读的方式打开二进制文件data2.dat
    fp = fopen("data2.dat", "rb");
    
    // 如果打开文件失败，输出提示信息并返回 
    if(fp == NULL) {
        printf("fail to open file to read\n");
        return;
    }
    
    // 从二进制文件data2.dat以数据块方式读取图书信息存储到结构体数组x
    i = 0;
    while(!feof(fp)) {
        number = fread(&x[i], sizeof(Book), 1, fp);
        if(number != 1)
            break;
        i++;
    }

    // 在屏幕上打印输出
    n = i;
    for(i = 0; i < n; ++i)
        printf("%d. %-40s%-20s\n", i+1, x[i].name, x[i].author);
    
    fclose(fp);
}

结果

存在换行符，会多读一次

3

 

#include <stdio.h>
#define N 5
#define M 80

void write();
void read_str();
void read_char();

int main() {
    printf("测试1: 把一组字符信息以字符串方式写入文本文件\n");
    write();

    printf("\n测试2: 从文件以字符串方式读取, 输出到屏幕\n");
    read_str();

    printf("\n测试3: 从文件以单个字符方式读取, 输出到屏幕\n");
    read_char();

    return 0;
}

void write() {
    char *ptr[N] = { "Working\'s Blues",
                     "Everything Will Flow",
                     "Streets of London",
                     "Perfect Day",
                     "Philadelphia"};
    int i;
    FILE *fp;

    fp = fopen("data3.txt", "w");
    if(!fp) {
        printf("fail to open file to write\n");
        return;
    }

    for(i = 0; i < N; ++i) {
        fputs(ptr[i], fp);
        fputs("\n", fp);
    }
    
    fclose(fp);
}

void read_str() {
    char songs[N][M];
    int i;
    FILE *fp;

    fp = fopen("data3.txt", "r");
    if(!fp) {
        printf("fail to open file to read\n");
        return;
    }

    for(i = 0; i < N; ++i)
        fgets(songs[i], 80, fp);

    for(i = 0; i < N; ++i)
        printf("%d. %s", i+1, songs[i]);
    
    fclose(fp);
}

void read_char() {
    char ch;
    FILE *fp;

    fp = fopen("data3.txt", "r");
    if(!fp) {
        printf("fail to open file to read\n");
        return;
    }

    while(!feof(fp)) {
        ch = fgetc(fp);
        if(ch == EOF)
            break;
        
        putchar(ch);
    }

    fclose(fp);
}

结果

其是转义字符

4

源代码

#include <stdio.h>
#include <ctype.h>

int main() {
    FILE *fp;
    char ch;
    int lines = 0;
    int words = 0;

    fp = fopen("data4.txt", "r");
    if (fp == NULL) {
        perror("Fail to open file");
        return 1;
    }

    while ((ch = fgetc(fp))!= EOF) {
        if (ch == '\n') {
            lines++;
        }
        if (!isspace(ch)) {
            words++;
        }
    }
    // 处理文件末尾没有换行符的情况
    if (wordss> 0) {
        lines++;
    }

    fclose(fp);

    printf("data4.txt统计结果：\n");
    printf("行数：%d\n", lines);
    printf("字符数(不计空白符)：%d\n", characters);

    return 0;
结果

 

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define NUM 80

typedef struct {
    int id;
    char name[20];
    char classes[20];
} Student;


void readStudents(Student students[]) {
    FILE *fp;
    fp = fopen("d:\\list.txt", "r");
    if (fp == NULL) {
        perror("打开文件失败");
        exit(1);
    }
    for (int i = 0; i < NUM; i++) {
        fscanf(fp, "%d %s %s", &students[i].id, students[i].name, students[i].classes);
    }
    fclose(fp);
}


void randomSelect(Student students[]) {
    srand((unsigned int)time(NULL));
    int selected[5];
   
    for (int i = 0; i < 5; i++) {
        int index;
        do {
            index = rand() % NUM;
        } while (index == selected[0] || index == selected[1] || index == selected[2] || index == selected[3] || index == selected[4]);
        selected[i] = index;
    }

    printf("随机随机点名名单\n");
    for (int i = 0; i < 5; i++) {
        printf("%d %s %s\n", students[selected[i]].id, students[selected[i]].name, students[selected[i]].classes);
    }

    char filename[50];
    printf("请输入文件名：");
    scanf("%s", filename);
    FILE *fp;
    fp = fopen(filename, "w");
    if (fp == NULL) {
        perror("打开文件失败");
        exit(1);
    }
    for (int i = 0; i < 5; i++) {
        fprintf(fp, "%d %s %s\n", students[selected[i]].id, students[selected[i]].name, students[selected[i]].classes);
    }
    fclose(fp);
    printf("保存成功！\n");
}

int main() {
    Student students[NUM];
    readStudents(students);
    randomSelect(students);
    return 0;
}

结果