#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
using namespace std;/*
文件结束标志: EOF --- feof()读写文件:
fgetc: file get char 以字符形式获取
fputc: file put char 以字符形式写到文件*/
int main()
{//定义文件指针FILE *fp;//打开文件fp = fopen("fopen_01.txt", "w+");//判断文件打开是否成功if (!fp) {printf("打开文件失败\n");exit(0);}//写的方式: 自己移动fputc('a', fp);fputc('b', fp);fputc('c', fp);//打开文件
    fclose(fp);//只读文件FILE *read = fopen("fopen_01.txt", "r");if (!read) {printf("打开文件失败\n");exit(0);}//读文件//fgetc(): 放回int值, 以字符形式获取int ch = fgetc(read);while (ch != EOF){putchar(ch);        //打印字符到命令行ch = fgetc(read);}printf("\n");fclose(read);return 0;}

#define _CRT_SECURE_NO_WARNINGS
#include <cstdlib>
#include <cstdio>
using namespace std;/*int fputs(char *str, FILE *fp);
char* fgets(char *str, int n, FILE *fp);*/
int main()
{FILE *fp = fopen("fgets_fputs_02.txt", "w+");if (!fp) {printf("打开文件失败");exit(1);}//写的方式: 自己移动int isok = fputs("Douzi is cute\n I love china!\n who are you?", fp);//返回非负值，表示成功printf("返回非负值表示成功: %d\n", isok);fclose(fp);FILE *read = fopen("fgets_fputs_02.txt", "r");if (!read) {printf("打开文件失败\n");exit(1);}//读文件char str[50] = "";//设置读取的长度while (fgets(str, 50, read)){puts(str);}//puts(str);
fclose(read);return 0;}

#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <iostream>
#include <cstdlib>
#include <cstring>
using namespace std;/*
//以二进制形式存储数据
int fwrite(void *buffer,unsigned size, unsigned count, FILE * fp)//以什么方式写进去就以什么方式读出 !!
int fread(void *buffer,unsigned size, unsigned count, FILE * fp)
*/struct student
{char name[20];int age;double num;
}mystudent;int main()
{//写文件FILE *fp = fopen("fread_fwrite_03.bat", "wb");if (fp == NULL) {printf("打开失败\n");exit(1);}while (true){printf("输入姓名-年龄-成绩:\n");scanf("%s%d%lf", &mystudent.name, &mystudent.age, &mystudent.num);//参数: 源起始位置, 写多少(字节), 写的次数, 目的地//     &mystudent, sizeof(struct student), 1, fpfwrite(&mystudent, sizeof(struct student), 1, fp);printf("是否继续?(Y/N)");//清除缓冲区//否则下面的字符无法输入，因为上面输入按下回车，"回车"会被下面的getchar()吃掉，而无法自己输入
        fflush(stdin);int ch = getchar();if (ch == 'N' || ch == 'n') {break;}}fclose(fp);//读取文件FILE *read = fopen("fread_fwrite_03.bat", "rb");if (!read) {printf("文件打开失败\n");exit(1);}//以二进制形式读取while (fread(&mystudent, sizeof(struct student), 1, read) > 0) {printf("姓名\t年龄\t成绩:\n");printf("%s\t%d\t%.2f\n", mystudent.name, mystudent.age, mystudent.num);}    fclose(read);return 0;}

#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <iostream>
#include <cstdlib>
#include <cstring>
using namespace std;/*
//以二进制形式存储数据
int fwrite(void *buffer,unsigned size, unsigned count, FILE * fp)//以什么方式写进去就以什么方式读出 !!
int fread(void *buffer,unsigned size, unsigned count, FILE * fp)：count: 知道有多少数据可以读取*/const int maxn = 1024 + 10;
struct student
{char name[20];int age;double num;
}stus[maxn];int main()
{////写文件FILE *fp = fopen("fread_fwrite_03.bat", "wb");if (fp == NULL) {printf("打开失败\n");exit(1);}int cnt;scanf("%d", &cnt);for (int i = 0; i < cnt; i++){printf("输入姓名-年龄-成绩:\n");scanf("%s%d%lf", &stus[i].name, &stus[i].age, &stus[i].num);        //清除缓冲区//否则下面的字符无法输入，因为上面输入按下回车，"回车"会被下面的getchar()吃掉，而无法自己输入
        fflush(stdin);}//参数: 源起始位置, 写多少(字节), 写的次数, 目的地//     stus, sizeof(struct student), cnt, fpfwrite(stus, sizeof(struct student), cnt, fp);fclose(fp);//读取文件FILE *read = fopen("fread_fwrite_03.bat", "rb");if (!read) {printf("文件打开失败\n");exit(1);}student read_demo[maxn];fread(read_demo, sizeof(struct student), cnt, read);for (int i = 0; i < cnt; i++){printf("姓名\t年龄\t成绩:\n");printf("%s\t%d\t%.2f\n", read_demo[i].name, read_demo[i].age, read_demo[i].num);}return 0;}

#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
using namespace std;/*
//printf: 多了指定位置
//参数: 指定位置, 与printf一样的格式化【类似%d这样】, 参数列表
int fscanf(FILE *fp, char *format, arg_list);
int fprintf(FILE *fp, char *format, arg_list);stdin:  标准输入 -- 键盘输入stdout: 标准输出 -- 屏幕输出FILE *: 自定义输入输出​
*/const int maxn = 20;
struct Student
{char name[maxn];int age;double score;
} mystu, stu[maxn];int main()
{//写文件////标准输入输出//printf("请输入姓名，年龄，成绩: \n");//fscanf(stdin, "%s%d%lf", mystu.name, &mystu.age, &mystu.score);//fprintf(stdout, "%s\t%d\t%.1f\n", mystu.name, mystu.age, mystu.score);FILE *fp = fopen("fscanf_fprintf_04.txt", "w+");if (!fp) {printf("failure!\n");exit(1);}while (true){printf("输入姓名-年龄-成绩: \n");//标准输入，写入文件 fscanf(stdin, "%s%d%lf", mystu.name, &mystu.age, &mystu.score);//写入文件fprintf(fp, "%s\t%d\t%.2f\n", mystu.name, mystu.age, mystu.score);fflush(stdin);printf("是否继续?(Y/N)");int ch = getchar();if (ch == 'N' || ch == 'n') {break;}}fclose(fp);//读文件FILE *read = fopen("fscanf_fprintf_04.txt", "r+");if (!read) {printf("failure\n");exit(1);}while (fscanf(read, "%s%d%lf", mystu.name, &mystu.age, &mystu.score) > 0){//标准输出fprintf(stdout, "%s\t%d\t%.2f\n", mystu.name, mystu.age, mystu.score);}fclose(read);}

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdlib>
#include <cstdio>
using namespace std;/*
fseek: fseek(文件类型指针, 位移量, 起始点) 位移量必须是long类型
起始点: (宏)
SEEK_SET 文件首 0;
SEEK_CUR 文件当前位置 1;
SEEK_END 文件尾部 2;以二进制形式存储数据
int fwrite(void *buffer,unsigned size, unsigned count, FILE * fp)
//以什么方式写进去就以什么方式读出 !!
int fread(void *buffer,unsigned size, unsigned count, FILE * fp)
*/
struct Student
{char name[20];int age;double num;
}stus[20];int main()
{//以二进制形式写文件FILE *fp = fopen("fseek_rewind_06.txt", "wb+");if (!fp) {printf("failure!\n");exit(1);}int N;cin >> N; for (int i = 0; i < N; i++){printf("输入姓名-年龄-分数:\n");scanf("%s%d%lf", stus[i].name, &stus[i].age, &stus[i].num);fflush(stdin);}//写入文件//存N个数据fwrite(stus, sizeof(struct Student), N, fp);//fseek(文件类型指针, 位移量, 起始点) 位移量必须是long类型//SEEK_SET 文件首 0;//注意点: 移动多个位置, long L :表示//正负: 往后- 往前+fseek(fp, 0, SEEK_SET);//移动到第二个数据位置
    Student tmp;fseek(fp, 1L * sizeof(struct Student), SEEK_SET);fread(&tmp, sizeof(struct Student), 1, fp);printf("第二个数据: \n");printf("%s\t%d\t%.2f\n", tmp.name, tmp.age, tmp.num);//移动到最后一个位置（之后无元素）fseek(fp, 0, SEEK_END);long size = ftell(fp);       //ftell：现在所在位置(表达这个文件的大小)int number = size / sizeof(Student);printf("有几个数据%d: \n", number);//移动到最后一个元素之前位置 位移量必须是long类型，需要类型转换fseek(fp, -1L * (long)sizeof(struct Student), SEEK_END);fread(&tmp, sizeof(struct Student), 1, fp);printf("最后一个元素: \n");printf("%s\t%d\t%.2f\n", tmp.name, tmp.age, tmp.num);//直接移动到文件开始位置Student stu[20];rewind(fp); printf("全部数据: \n");int len = fread(stu, sizeof(struct Student), N, fp);for (int i = 0; i < len; i++){printf("%s\t%d\t%.2f\n", stu[i].name, stu[i].age, stu[i].num);    }fclose(fp);return 0;}