Linux作业

#include
#include
#include
#include
#include

struct stu

{
char name[20];
long sno;
int age;
};

main()

{
struct stu per[3];
struct stu info;
int fd;
int i,n;
char c;
int option;
off_t off;

fd = open("a.txt",O_RDWR|O_CREAT,00777); //open fire
if(fd==-1) //judge input fire??
{
perror("fail to open\n");
exit(1);
}

printf("please inpit information of three numbers:\n ");
for(i=0;i<3;i++)
{
printf("di %d ge student name number age :\n",i+1);
scanf("%s%d%d",&per[i].name,&per[i].sno,&per[i].age);
}
for(i=0;i<3;i++) //write fire
{
if(write(fd,&per[i],3*sizeof(struct stu))==-1)
{
perror("fail to write");
exit(1);
}
}
close(fd);

fd = open("a.txt",O_RDWR|O_CREAT,00777); //choose fire
do
{
printf("choose information of student(1,2,3):");
scanf("%d",&option);
off = lseek(fd,(option-1)*sizeof(struct stu),SEEK_CUR);
n = read(fd,&info,sizeof(struct stu));
if(n==-1)
{
perror("fail to read");

}
printf("%s %d %d",https://www.wendangku.net/doc/af6009169.html,,info.sno,info.age);
printf("\n");
off = lseek(fd,0,SEEK_SET);
printf("go on select please input y :");
scanf("%s",&c);
}
while(c=='y');
close(fd);
}