1.9

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<string.h>
#define MAX 100


int read_line(int fd, char *buf, int count)
{
int i;
char ch;


for(i = 0; i < count; i++)
{
        if((read(fd,&ch,1)) < 0)
{
perror("read error!\n");
exit(1);
}


if(ch == '\n')
{
             buf[i] = '\0';
return i;
}


buf[i] = ch;
}


buf[i - 1] = '\0';

return count;
}


int main()
{
int i;
int fd;
int w_count;
int r_count;
char filename[MAX];


char r_buf[MAX];
char w_buf[MAX];


printf("Please input filename:\n");
scanf("%s",filename);


if((fd = open(filename, O_CREAT | O_RDWR, 0755)) < 0)
{
perror("open error!\n");
exit(1);
}



    for(i = 0; i < 3; i++)
{
        memset(w_buf,0,sizeof(w_buf));
scanf("%s",w_buf);

if((w_count = write(fd,w_buf,strlen(w_buf))) < 0)
{
perror("write error!\n");
exit(1);
}
else
{
write(fd,"\n",1);
}
}
    
    lseek(fd,0,SEEK_SET);
#if 0
if((r_count = read(fd,r_buf,sizeof(r_buf))) < 0)
{
perror("read error!\n");
exit(1);
}
else
{
r_buf[w_count * 3 + 3] = '\0';
printf("read data: %s\n",r_buf);
}
#endif


for(i = 0; i < 3; i++)
{
        memset(r_buf,0,sizeof(r_buf));
read_line(fd,r_buf,100);
printf("read data: %s\n",r_buf);
}


close(fd);


return 0;
}