33. 使用fread()/fwrite()往文件中写入结构体，从文件中读出结构体

//读写结构体
#include <stdio.h>
typedef struct student
{
    int num;
    char name[30];
    char sex;
    float math;
    float english;
    float chinese;

}Stu;

Stu s[5] =
{
    1001,"wukong",'x',99,99,99,
    1002,"songjiang",'x',99,22,11,
    1003,"baoyu",'x',79,33,100,
    1004,"liudehua",'y',100,100,88,
    1005,"zhaosi",'z',33,34,12
};

int main(void)
{

    //往文件中写入结构体
    FILE* pf = fopen("G:/qtcode/stu.data","w+");
    if(pf == NULL)
        exit(-1);
#if 1
    //写入方式1
    int i;
    for(i = 0;i<sizeof(s)/sizeof(*s);i++)
    {
        fwrite((void*)(&s[i]),sizeof(Stu),1,pf);
    }
#endif
#if 0
    //写入方式2
    fwrite((void*)s,sizeof(s),1,pf);

#endif
#if 0
    //写入方式3
    fwrite((void*)s,sizeof(Stu),5,pf);

#endif



    rewind(pf);
    //从文件中读结构体
#if 0
    //读出方式1
    Stu buf;
    while( fread((void*)&buf,sizeof(Stu),1,pf) )
    {
        printf("num = %d
",buf.num);
        printf("name = %s
",buf.name);
        printf("sex = %c
",buf.sex);
        printf("math = %.2f
",buf.math);
        printf("english = %.2f
",buf.english);
        printf("chinese = %.2f
",buf.chinese);
        printf("--------------
");
    }
#endif

#if 0
    //读出方式2
    Stu buf[3];
    int j,n;
    while((n = fread((void*)buf,sizeof(Stu),3,pf)) > 0)
    {
        for(j = 0;j < n;j++)
        {
            printf("num = %d
",buf[j].num);
            printf("name = %s
",buf[j].name);
            printf("sex = %c
",buf[j].sex);
            printf("math = %.2f
",buf[j].math);
            printf("english = %.2f
",buf[j].english);
            printf("chinese = %.2f
",buf[j].chinese);
            printf("--------------
");
        }
    }
#endif
    
#if 0
    //读出方式3
    Stu buf[5];
    int j;
    fread((void*)buf,sizeof(Stu),5,pf);
    for(j = 0;j < 5;j++)
    {
        printf("num = %d
",buf[j].num);
        printf("name = %s
",buf[j].name);
        printf("sex = %c
",buf[j].sex);
        printf("math = %.2f
",buf[j].math);
        printf("english = %.2f
",buf[j].english);
        printf("chinese = %.2f
",buf[j].chinese);
        printf("--------------
");
    }
#endif
    return 0;
}