#include<stdio.h>
#include<stdlib.h>
#define N 5
struct students{
char name[10];
int age;
double tizhong;
}student[N];
void save()
{
    FILE*fp;
    if((fp=fopen("xxg.txt","wb"))==NULL)
        {printf("文件打开失败\n");exit(0);}
        for(int i=0;i<N;i++)
            if(fwrite(&student[i],sizeof(struct students),1,fp)!=1)
            printf("文件写入失败！\n");
            fclose(fp);
}
void out()
{
    FILE*fp;
    if((fp=fopen("xxg.txt","rb"))==NULL)
        {printf("文件打开失败\n");exit(0);}
        for(int i=0;i<N;i++)
            {fseek(fp,i*sizeof(struct students),0);//随机读取数据，在fseek中，起始点为0.
            fread(&student[i],sizeof(struct students),1,fp);
            printf("%-10s%-4d%4.2f\n",student[i].name,student[i].age,student[i].tizhong);
            }
            fclose(fp);
}

int main()
{
    printf("请输入学生信息！\n");
    for(int i=0;i<N;i++)
    scanf("%s%d%lf",student[i].name,&student[i].age,&student[i].tizhong);
    save();
    printf("输出文件信息\n");
    out();
    return 0;
}

谢谢